Preheat the oven to 350°F (175°C). Grease and flour cake pans.

In a large bowl, cream together the softened butter and sugar until light and fluffy.

Add the eggs one at a time, beating well after each addition.

Mix in the vanilla extract.

In another bowl, whisk together the flour, baking powder, and salt.

Add the dry ingredients to the creamed mixture alternately with the milk, beginning and ending with flour mixture. Mix until just combined.

Pour the batter into the prepared pans and smooth the top.

Bake for 30 minutes or until a toothpick inserted in the center comes out clean.

Let the cakes cool in the pans for 10 minutes, then turn them out onto wire racks to cool completely.

For the frosting, beat together the softened butter and powdered sugar until smooth.

Add the heavy cream and vanilla extract, mixing until combined.

Add blue food coloring to the desired shade.

Frost the cooled cakes and decorate with edible glitter or sprinkles if desired.