Oatmeal Sandwich Cookies

The ultimate Oatmeal Sandwich Cookies! This easy recipe for oatmeal and marshmallow cookie sandwiches is essentially a copycat of Little Debbie's Oatmeal Creme Pies. Super soft and chewy spiced molasses oatmeal cookies sandwiched together with a light and airy marshmallow fluff filling.

Jump to:

• Why these work
• Ingredient Notes
• How to Make Oatmeal Sandwich Cookies
• Softened Butter versus Melted Butter
• Marshmallow Filling
• Assembling Oatmeal Sandwich Cookies
• Variations
• Expert Baker Tips
• FAQs
• Oatmeal Sandwich Cookies

Why these work

• Inspired by Little Debbie's famous Oatmeal Creme Pies - these sandwich cookies are directly based on the American lunchbox classic! Combining classic oatmeal cookies with a marshmallow-y buttercream filling.
• Soft and chewy molasses oatmeal cookies - an easy oatmeal cookie recipe made with melted butter and molasses, makes these super soft and chewy sandwich cookies.
• A quick copycat creme pie filling - my simple marshmallow fluff buttercream brings these sandwich cookies together with plenty of fluff and flavour.

Ingredient Notes

To make my soft oatmeal sandwich cookies, you'll need

• Butter - unsalted butter, melted. You can substitute with salted butter for this recipe, but salted butter will add extra salt to the overall flavour, so you may want to decrease the additional salt added.
• Molasses - or dark treacle. This will give your cookies a cozy flavour and help to create a chewy texture.
• Sugar - granulated sugar or caster sugar.
• Light brown sugar - sometimes called muscovado, firmly packed. Using brown sugar will add to the molasses notes in the cookies. You can use dark brown sugar here, but I find it overpowers the sandwich cookies with molasses, which takes a little away from the light and fluffy filling.
• Egg - a large egg, ideally at room temperature for adding to the dough.
• Vanilla
• Flour - all purpose flour or plain flour work in this recipe.
• Baking Soda
• Salt
• Cinnamon
• Nutmeg
• Rolled oats

How to Make Oatmeal Sandwich Cookies

This is really a one-bowl recipe.

• Start by melting the butter in a small saucepan along with the molasses.
• Then whisk the butter mixture into the sugars and beat together until fully emulsified (about 2 minutes). (image 1 below)
• Add the egg and vanilla, beating to combine.
• Next add the flour, baking soda, salt and spices. Whisk until just combined. (image 2 below)
• Add the oats and stir together into a dough using a spatula or wooden spoon. (image 3 below).
• Spoon the runny oatmeal cookie batter well spaced on a piece of parchment or silicone baking mat.
• Bake in the centre of a preheated oven for about 8-10 minutes until the edges just start to darken.
• Remove from the oven and allow to cool for a few minutes on the tray before transferring to a wire rack to finish cooling.

Softened Butter versus Melted Butter

The consistency of butter matters in baking.

In most cases, you want room temperature ingredients (including butter) so that these mix well together and bake evenly. For cookies, for example, room temperature butter helps keep cookies from spreading too much. In fact, many recipes will suggest chilling the scooped dough before baking, to reduce the spread even further and produce nice thick and chewy finished products. This is the same logic for pastry crusts like my All Butter Shortcrust.

The style of a knock off Little Debbie's Creme Pie demands something a bit different. The goal here is actually a thin cookie, with a bit of a soft bendy finish. This means melting the butter is key.

Melting the butter before using it produces a wetter dough and encourages more spread when baking. The result is a softer thinner final biscuit.

Marshmallow Filling

The filling for a classic oatmeal cream pie is a bit of a contentious question. Many recipes will simply call for a well whipped vanilla buttercream. But, for me the Little Debbie's original has a marshmallowy quality, that demands a bit of marshmallow in the filling.

Ingredients

My marshmallow buttercream is quick and easy to whip up with the following:

• Butter - unsalted butter, softened at room temperature. It is important that this is unsalted for the filling to avoid excess saltiness in these cookie sandwiches.
• Powdered sugar - or icing sugar. It is best practice to sift this for a buttercream to give yourself a smoother creamier finish. It is particularly important to do this if yours is especially lumpy, otherwise you will end up with small clumps of powdered sugar in your final icing.
• Marshmallow fluff - a bit of marshmallow cream goes a long way to flavouring and adding a fantastically sticky fluffy texture here.
• Vanilla extract
• Milk - I like to use full fat or whole milk when baking. It gives that extra little bit of rich creaminess. For this buttercream, you can use 2% or semi-skimmed, but I would recommend against 1% or skimmed milk as it tends to be too watery.

Process

Making this marshmallow buttercream is very similar to my standard American buttercream recipe, with one big exception:

You want to whip or whisk the ingredients here - don't worry about adding air. In traditional buttercream, you aren't looking to whip the ingredients into something fluffy as this can cause air bubbles in decorating. For this cream pie filling, you do want a light and fluffy finish.

• Start by using a handheld electric beater to beat together the butter, marshmallow fluff and powdered sugar. Be careful as the thickness of the fluff might initially make beating difficult, but once this is incorporated it will begin to be smooth.
• Add the vanilla and the milk last to form a light and smooth frosting.
• Tip: You can add extra milk if you feel your frosting is too thick or more powdered sugar if you feel it is over runny.

Assembling Oatmeal Sandwich Cookies

Once you have your cookies and cream, you need to assemble the oatmeal cream pie. This is best done with a piping bag.

• Start by filling your bag with the frosting and then cutting off the tip so that you have about a ½" opening.
• Pipe onto the flat base of one of your oatmeal cookies.
• Sandwich this with the base of another cookie.
• Repeat this process until you have paired all of your cookies into sandwiches.

Variations

• Cookie sandwich sizes - this recipe makes about fourteen average size cookie sandwiches, or seven giant oatmeal cookie sandwiches. For the giant oatmeal cream pie, I used an OXO #40 Good Grips dough scoop. This dollops out about 1.5 tablespoons of batter, which spread to large cookies. If you want to make smaller cookies, you can either use a smaller scoop or a kitchen spoon to portion these. As the dough is very wet, they will spoon out and spread easily.
• Different filling - this recipe is essentially a copycat of the Oatmeal Creme Pie of Little Debbie fame. These use a marshmallow-y vanilla filling and therefore the filling here is marshmallow based. You can absolutely use a different filling for your oatmeal cookie sandwiches! Try Cinnamon Buttercream, Dulce de Leche Frosting or maybe a Rum Buttercream with chopped nuts like in my Gingerbread Cookie Sandwiches.
• Play around with spicing - oatmeal cookies are a great cookie dough to spice up to your own taste preferences! I'm a huge cinnamon fan, but if you like ginger or maybe want to add pumpkin pie spice, you can add a bit to the dough in these cookies.
• Add nuts, raisins or chocolate chips - you can add a bit of extra texture and flavour to these cookies with chopped nuts, chocolate or dried fruit, such as raisins. Pecans in particular go nicely with these cookies, just be sure to chop them up into small pieces for adding to the dough.
• Dairy free - you can substitute the butter in the cookie dough for a flavorless oil or a dairy free butter substitute and will get similar results. As there is no milk in the cookie, you will not need to make other substitutes to achieve a dairy free oatmeal sandwich cookie. You will, however, need to make further alterations to the filling, such as using a non-dairy butter or shortening.

Expert Baker Tips

Tricks for Thin, Chewy Sandwich Cookies

So, one of the trademark elements of the classic Little Debbie's Oatmeal Creme Pie is the super soft thin oatmeal cookie. This can be difficult to recreate at home, especially when most cookie recipes encourage you to aim for a thicker biscuit.

There are a few key tricks to making these soft thin cookies:

• Use melted butter, not just softened.
• Whisk the sugars, molasses and butter together until fully incorporated. The butter will initially try to separate from the sugars, but with a bit of whisking this will all come together as the sugars begin to dissolve into the butter.
• Avoid over-baking and take these out as soon as they start to golden at the edges.
• Let the cookies cool for five to ten minutes on the baking tray before removing to a wire rack. This makes for a chewier cookie than if they are immediately transferred to the rack.

Advice for Assembly

• Always pre-pair your cookies when sandwiching. There is no better way to be prepared than to pre-pair! (I couldn't resist...). Anyway, matching up your cookies before you begin to fill means that you have the best chance of ensuring nicely even cookie sandwiches and you know exactly how far your filling needs to go.
• You don't need special equipment for filling your cookie sandwiches. If you don't have a piping bag, you can make your own DIY piping bag with any square or rectangular plastic bag. Simply fill this with your frosting and cut off a corner as you would cut the tip of the piping bag.

FAQs

If you like this recipe, check out some other oatmeal favorites:

• Edible Oatmeal Cookie Dough
• Oatmeal Coconut Chocolate Chip Cookies
• Date Filled Oatmeal Cookies
• Classic Oatmeal Cookies
• No Bake Cookies without Peanut Butter
• Oat Crumble Topping