Add your butter and sugars to a large mixing bowl and beat until light and fluffy. This will take about 2 minutes using a stand mixer and paddle attachment or a little less time using handheld electric beaters.
1¼ cup unsalted butter, ¾ cup light brown sugar, ½ cup superfine granulated sugar
Add the egg and vanilla, beating to combine.
1 large egg, 1 teaspoon vanilla bean paste
Next sift your dry ingredients into the dough - these are the flour, baking soda, cinnamon and cardamom. Mix with a spatula just until combined and no patches of flour remain.
1½ cups all purpose flour, 1 teaspoon baking soda, ½ teaspoon ground cinnamon, ½ teaspoon ground cardamom
Add in the oats, pistachios and chocolate, mixing until well distributed.
1½ cups rolled oats, 1 cup dark chocolate chips, 1 cup pistachios, shelled and unsalted
Using a cookie scoop, pre-scoop your cookie dough balls and place these on a tray in the refrigerator to chill for a couple of hours.
Once your dough is well chilled, preheat the oven to 375ºF and place balls of dough well spaced (about 2" apart) on a parchment lined baking sheet. For a decorative finish, gently press the balls of dough to lightly flatten and add a couple of pistachios and chocolate chips on top.
Bake in the center of your pre-heated oven for about 12-15 minutes until starting to go golden at the edges. Remove from the oven and immediately sprinkle with a little flaked sea salt. Allow to cool on the cookie sheet for a few minutes before transferring to a wire wrack to finish cooling