2 ½ cups (13oz/360g) all-purpose flour

1 tablespoon baking powder

½ cup (3.5oz/100g) granulated sugar

1 cup (8oz/225g) unsalted butter ((softened))

2 large egg yolks ((at room temperature))

¼ cup (2floz/60ml) full fat sour cream

1 teaspoon vanilla extract

1 cup (8floz/240ml) Nutella, strawberry jam, or poppy seed filling

2 large egg whites

½ cup (2 ½oz/70g) powdered sugar for dusting the cookies ((optional))

Line 2 large baking sheets (18 x 13-inch) with parchment paper, set aside.

In a large bowl, sift the flour and baking powder, mix in the sugar.

Add the butter, egg yolks, sour cream and vanilla extract and use your hands to mix the ingredients together until there are no lumps of butter and a soft, smooth dough is formed.

Divide the dough into two parts, and roll one part into ¼-inch thick.

Use a 3-inch circle cookie cutter to cut the dough and dollop 1 teaspoon of Nutella filling at the center of each cookie.

Brush the edges of the cookies with the egg white, then use your pointer finger and thumb to pinch the dough in three corners creating a triangle.

Place the cookies on the baking sheet and preheat the oven to 350oF (180oC). Place the pan in the refrigerator or freezer while the oven is preheating.

Bake for 12-14 minutes or until the cookies are puffed and the bottom is golden brown. Remove from the oven and allow to cool before dusting with powdered sugar and serving.