Preheat the oven to 350°F.

Whisk the ground hazelnuts and flour together.

Beat the butter and sugar together on medium speed until light and fluffy, 3-4 minutes. Add the extracts and beat to blend.

Add the flour and ground hazelnuts to the butter and sugar, mixing only until they are incorporated.

Make small balls of the dough and place them 2 inches apart on a parchment lined baking sheet. Use your pinkie finger or the end of a round handled wooden spoon to poke a hole in the center of each cookie. Be careful to only poke about halfway at most so that the centers don't burn.

Bake for 15-18 minutes, rotating the pans front to back at the midway point. When the cookies are done, they'll be ever-so-slightly golden. If you think they are golden, but you're not sure, take them out anyway.

Let the cookies rest for about 2 minutes before transferring them to a wire rack to cool. Sift powdered sugar over them.

Warm the jam to make it easy to fill the cookies.

To store, layer with parchment or waxed paper.