01 -
Preheat oven to 175°C and line a baking sheet with parchment paper.
02 -
In a large mixing bowl, beat the softened butter and granulated sugar together using an electric mixer or hand whisk until the mixture is light and fluffy.
03 -
Add the egg and vanilla extract to the creamed mixture, beating thoroughly until well blended.
04 -
In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry mixture into the wet batter, stirring until just combined.
05 -
Take small portions of dough and flatten each into a disc. Place one teaspoon of blueberry jam in the center, fold the dough over, and pinch the edges to seal.
06 -
Arrange the filled cookies evenly on the prepared baking sheet. Bake for 12 to 15 minutes, or until the edges are lightly golden. Transfer to a wire rack and allow to cool completely.
07 -
In a small bowl, whisk together the powdered sugar and fresh lemon juice until a smooth glaze forms.
08 -
Drizzle the lemon frosting over the cooled cookies and sprinkle with blue sugar crystals before serving.