Preheat the oven to 350°F (175°C). Grease and line two 8-inch round cake pans and set aside.

Whisk together the flour, baking powder, and salt in a medium bowl until evenly combined.

Beat the softened butter and granulated sugar until light and fluffy. Add eggs one at a time, mixing well after each addition, then stir in vanilla.

Add the dry ingredients and milk to the butter mixture in alternating additions, beginning and ending with the dry ingredients. Mix until just combined.

Divide the batter evenly between the prepared pans and bake for 22–25 minutes, or until a toothpick comes out clean.

Let cakes cool in the pans for 10 minutes before turning out to cool completely.

In a saucepan combine 2 cups blueberries, 1/4 cup sugar, and lemon juice. Cook over medium heat until the blueberries release juices and start to break down.

Stir in the cornstarch slurry and cook until slightly thickened; cool completely.

Chill your bowl and beaters. Whip 2 cups heavy cream with 1/4 cup powdered sugar and 1 tsp vanilla extract to stiff peaks.

Place one cake layer on a serving plate. Spread half the blueberry filling, then a layer of whipped cream. Top with the second cake layer, cover with remaining cream, and garnish if desired.

Chill for at least 2 hours before serving to set.