In a large mixing bowl, combine the softened butter and powdered sugar. Use a wooden spoon or spatula to combine until they are creamed together and very smooth. Add the egg and egg yolk, and the vanilla extract. Stir to combine.

Add the almond flour, all purpose flour, baking powder and kosher salt to the bowl. Use a spatula or wooden spoon to gently fold all of the ingredients together until a dough forms and there are no dry patches of flour. The dough should still be soft and slightly sticky.

Wrap the dough in plastic wrap, and chill for at least 45 minutes, or up to 2 days.

Preheat the oven to 350°F.

Dust your clean work surface well with flour. Divide the dough into two pieces and sprinkle the top of the dough with flour as well. Roll out the dough to 1/4-inch thickness. Use a 2-inch round cookie cutter to stamp out as many circles as possible. Place the shaped cookies on a rimmed baking sheet lined with parchment paper, about 1-inch apart (they don’t spread much while baking).

Then use a small round cutter (I used a piping tip) to stamp out a small hole from half of the cookies for the “window” on top of the sandwich cookies.

Re roll your scraps of dough, handling and kneading the dough very minimally.

Bake the cookies for 13-14 minutes until the edges are just slightly golden brown.

Allow the cookies to cool completely, then use a knife or an offset spatula to spread about a tablespoon of Nutella hazelnut spread on top of the solid bottom cookies.

Optional: dust the group of top cookies with powdered sugar, the place on top of the Nutella filled cookies.

Enjoy!

These cookies can be stored at room temperature for up to 3 days.