Stir almond flour, softened butter, powdered sugar, vanilla, and a few drops of almond extract until you have a thick, spreadable paste. If it is too stiff, add 1 teaspoon of milk. Set aside.

Beat room temperature butter with granulated and brown sugar until light and creamy.

Mix in the egg, vanilla, and a small splash of almond extract.

Whisk flour, baking powder, and salt. Add to the wet mixture just until combined. The dough should be soft but not sticky.

Pop the dough in the fridge for 20 to 30 minutes while you preheat the oven to 350°F (175°C). Line two baking sheets with parchment.

Scoop dough into 1.5 tablespoon balls. Roll lightly in granulated sugar.

Press a thumbprint into each dough ball, then spoon in a generous amount of almond filling.

Press sliced almonds over the top, and sprinkle with sugar.

Bake for 10 to 12 minutes, until edges are set and lightly golden. Centers should still look soft.

Let them sit on the tray for 5 minutes, then move to a rack. Dust with powdered sugar if desired.