Step 1: Prepare your oven and pan
Preheat your oven to 350°F (175°C). Line a cupcake pan with 12 paper liners.

Step 2: Mix dry ingredients
In a medium bowl, sift together the flour, baking powder, and salt.

Step 3: Cream butter and sugar
In a large bowl, use an electric mixer to cream the softened butter and sugar until light and fluffy—about 3-4 minutes.

Step 4: Add eggs and vanilla
Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.

Step 5: Combine wet and dry ingredients
Add the dry ingredients in three parts, alternating with the milk, starting and ending with the flour mixture. Mix gently until just combined — overmixing can lead to dense cupcakes.

Step 6: Fold in sprinkles
Gently fold in ½ cup of rainbow sprinkles. These create little bursts of color inside the cupcake.

Step 7: Fill the cupcake liners
Spoon the batter evenly into the prepared liners, filling about two-thirds full.

Step 8: Bake
Bake for 18-22 minutes or until a toothpick inserted in the center comes out clean. Allow cupcakes to cool completely on a wire rack before frosting.

Step 9: Make the frosting
Beat butter until creamy. Gradually add powdered sugar, one cup at a time, alternating with cream and vanilla, until you reach a fluffy but spreadable consistency.

Step 10: Frost and decorate
Pipe or spread the frosting on cooled cupcakes and generously top with more sprinkles for the ultimate festive look.