Funfetti Cupcakes

1. Preheat oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.
2. In a large bowl, beat 1/2 cup unsalted butter until light and fluffy. Gradually mix in 1 1/2 cups granulated sugar, then add eggs one at a time, beating well after each addition. Stir in 1 1/2 tbsp vanilla.
3. In a separate bowl, whisk together 1 1/2 cups all-purpose flour, 1 1/2 tsp salt, and 1 1/4 tsp baking powder. Gradually alternate adding the dry ingredients and 1/2 cup buttermilk to the wet ingredients, starting and ending with the dry ingredients. Mix until just combined.
4. Gently fold in 1/2 cup rainbow sprinkles.
5. Fill the cupcake liners about two-thirds full with batter. Bake for 15 to 17 minutes, or until a toothpick inserted into the center comes out clean. Let the cupcakes cool completely on a wire rack.
6. For the buttercream: In a medium bowl, beat 1/2 cup unsalted butter until light and fluffy. Gradually add 2 1/2 cups powdered sugar, 1 tbsp vanilla, and 1/2 tsp salt. Add 1 to 2 tablespoons of heavy cream, beating until the frosting is light and fluffy and reaches desired consistency.
7. Once cupcakes are completely cool, frost them with the prepared buttercream and top with extra sprinkles if desired.