Preheat the oven to 350°F.
Start the blueberry topping by combining the blueberries, 1 cup granulated sugar, and a splash of water in a pot on the stovetop. Bring to a boil and then reduce to a simmer. Let simmer for 20 min.
Meanwhile, start the cake batter. Cream together the butter and 1 cup of granulated sugar. Then add in the vanilla, eggs, and milk. Once combined, sift in the flour and baking powder.
Spread the batter over two greased 9x12 pans and bake for 25-30 min until a toothpick comes out clean. Allow to cool for 5 min and then remove from the pan and allow to cool completely.
To make the whipped cream, whip the heavy cream and powdered sugar until stiff peaks form.
Assemble the cakes by cutting out the cake into heart shapes, drizzle with cooled blueberry topping, whipped cream, and top with another heart cake and whipped cream.