Preheat the oven to 375 degrees F (190 degrees C). Spray a mini muffin tin with cooking spray and set aside.
Unroll thawed puff pastry sheet on a lightly floured work surface. Roll into a large rectangular sheet, and using a pizza cutter or knife, cut into 24 equal pieces. Press each piece into a muffin cup, and use a fork to prick the bottom several times.
Cut Brie cheese into 24 small cubes, and place a cube into each muffin cup. Top each with about 1/2 teaspoon of lemon curd.
Place muffin tin in the preheated oven and bake until the pastry is puffed and the corners turn golden brown, 12 to 14 minutes.
Remove from the oven and cool in the pan for about 5 minutes. Remove bites to a serving plate, top each with a blueberry, dust with confectioners' sugar, and garnish with a small mint leaf, if desired.