01 - Preheat your oven to 350°F. Grease and line two 9-inch round cake pans with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, and salt until well blended.
03 - In a large bowl, beat butter and sugar together on medium-high speed until light and fluffy, about 3 to 4 minutes.
04 - Add eggs one at a time, beating well after each addition. Mix in vanilla bean paste until fully incorporated.
05 - Add flour mixture in three parts, alternating with milk, beginning and ending with flour. Mix until just combined; do not overmix.
06 - Divide batter evenly between prepared pans. Smooth tops with a spatula. Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.
07 - Cool cakes in pans for 10 minutes, then turn out onto wire racks to cool completely before frosting.
08 - Beat butter on medium speed until creamy, about 2 minutes. Gradually add powdered sugar on low speed. Add milk, vanilla, and salt; beat on high for 3 minutes until fluffy.
09 - Place one cake layer on a serving plate. Spread a generous layer of buttercream on top. Place the second layer over the first, then frost the top and sides evenly.
10 - Decorate with sprinkles or edible flowers if desired. Slice and serve.