Begin by placing the flour, almond flour, salt and sugar in a mixing bowl. Stir this together.
Then add the cubes of chilled butter. Using your fingers, rub this into the flour mixture.
Add the almond extract followed by about ½ tablespoon of chilled water. Stir together with a knife and then your hands, adding a little extra water until you are able to knead it together as a small ball of dough. (See note)
Wrap the dough in plastic wrap and place in the refrigerator for about 1 hour to thoroughly chill. Meanwhile, you can make your blood orange curd if making from scratch.
Once the dough has chilled, remove from the refrigerator. Removing the plastic wrap, divide the dough ball in half and gently knead into a smaller round. Roll each piece out on a floured work surface until about ⅛" thick (.25cm) and use these to line two 4" loose bottomed tartlet tins, allowing the dough to overhang the sides. Return to the refrigerator to chill while you preheat the oven to 350°F (175C/155C Fan)
When ready to bake, prick the dough all over the base and sides with a fork and line each tart with a piece of parchment paper weighted down by baking beans or rice.
Place the tartlet shells in the oven to bake for 15 minutes. Then remove the parchment paper and beans, return to the oven and bake for a further 15 minutes until lightly golden.
Taking the blind baked tart shells out of the oven, carefully trim the overhanging edges and knock away excess flaky almond crust.
Divide the blood orange curd between the two shells and smooth with a spatula. If the curd is fresh made, allow to cool.
When ready to top with meringue, place the sugar and water in a saucepan over a medium high heat, stirring occasionally until the sugar dissolves. Continue cooking until the sugar syrup reaches 240°F (115C).
While the syrup is heating, beat the egg whites in a large mixing bowl with an electric hand mixer until they are foamy and reaching soft peak stage.
When the syrup reaches temperature, remove from the heat and slowly steadily pour down the side of the bowl into the egg whites while continuing to beat.
After emptying the syrup into the egg whites, beat until the egg whites are stiff peaks and the bowl has cooled to the touch.
Dollop or pipe the meringue on top of the curd, ensuring that it reaches the edges of the crust. Chill for a couple of hours and serve with a piece of candied blood orange or some zest for decoration.