Preheat the oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.
In a large bowl, cream the unsalted butter and granulated sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
In a separate bowl, sift together the all-purpose flour and baking powder.
Alternately add the flour mixture and whole milk to the creamed mixture, beginning and ending with flour. Mix until just combined.
Divide the batter evenly among the prepared pans and bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then turn out onto wire racks to cool completely.
To make the vanilla buttercream frosting, whip the heavy cream until stiff peaks form. In another bowl, cream the unsalted butter until smooth, gradually add powdered sugar, and continue beating until fluffy.
Fold the whipped cream into the butter and sugar mixture gently to create a smooth, creamy frosting.
Divide the frosting into three portions. Tint one portion pastel pink, another pastel blue, and leave the last white.
Place the first cake layer on the white cake stand. Spread a layer of frosting evenly on top. Repeat with the second and third layers.
Use the pink and blue frosting to pipe rosettes around the cake, alternating colors.
Decorate the top tier with fondant numbers ’18’ and sprinkle edible gold glitter lightly over the cake for an elegant finish.