Preheat the oven to 350°F (175°C) and lightly grease a 9×13 inch sheet cake pan.

Whisk together flour, baking powder, and salt in a medium mixing bowl.

Cream the unsalted butter and sugar in another bowl until light and fluffy. Add in the eggs one at a time, followed by the vanilla extract.

Combine the wet and dry ingredients gradually, adding milk until the batter is smooth and creamy.

Pour the batter into the prepared pan and bake for 20–25 minutes, or until a toothpick inserted in the center comes out clean.

Cool the cake completely in the pan before handling.

Prepare the blueberry filling by cooking blueberries, sugar, lemon juice, and cornstarch over medium heat until thickened.

Cut the cooled cake into mini rounds using a sharp cookie cutter.

Mix the powdered sugar, lavender-infused milk, and optional food coloring until you achieve a smooth glaze consistency.

Glaze each mini cake by pouring the lavender glaze over the top and garnish.