Preheat your oven to 350°F (175°C) and prepare two 9-inch round cake pans by greasing and dusting with flour.

In a medium bowl, whisk together flour, baking powder, and salt.

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

Add eggs one at a time, mixing well after each addition, then stir in vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with milk, and mix until just combined.

Divide the batter evenly between the prepared pans and smooth the tops.

Bake for 25-30 minutes or until a toothpick inserted comes out clean. Let cool in pans for 10 minutes, then transfer to wire racks to cool completely.

For the frosting, beat the softened butter until creamy, then gradually add powdered sugar and heavy cream, mixing until smooth. Stir in vanilla extract.

Frost the top of one cake layer, place the second layer on top, and frost the top and sides of the cake.

Decorate with sprinkles and add birthday candles before serving.