Beat the butter and confectioners sugar using a hand or stand mixer starting on low speed and increasing the speed to medium once most of the sugar is blended into the butter. Then beat until light and fluffy (about 3 minutes).

Beat in the egg yolk and vanilla.

Add the flour, cornstarch and salt and mix in on low speed until the dough comes together (the dough will be very soft.)

Wrap the dough in plastic and chill for at least 2 hours before rolling.

Preheat the oven to 325°F/160°C and line 2 baking trays with parchment paper.

On a lightly floured work surface, knead the dough slightly to soften and then roll the dough out to about ¼-inch (6 mm) thick.

Using a two inch cookie cutter, cut out the cookies and place them onto the trays. Then on half the cookies, cut the center out using a mini cookie cutter.

Bake the cookies for 8-10 minutes, until they just start to brown at the edges. Allow the cookies to cool on the trays before dusting the half with the center cut with powdered sugar.

Spread about 1 teaspoon of your filling on the bottoms of the solid cookies and then gently press the cut out cookies on top of the filling.