Preparation Steps

• Preheat oven to 350°F (175°C). Line a 12-cup muffin tin with cupcake liners.
• In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt.
• In a separate bowl, cream together the softened butter until light and fluffy.
• Beat in the eggs one at a time, then stir in the vanilla extract.
• In a small bowl, whisk together the milk and sour cream.
• Alternately add the dry ingredients and the milk mixture to the butter mixture, beginning and ending with the dry ingredients. Mix until just combined.
• Gently fold in the rainbow sprinkles.
• Divide the batter evenly among the cupcake liners, filling each about two-thirds full.
• Bake for 20-22 minutes, or until a wooden skewer inserted into the center comes out clean.
• Let the cupcakes cool in the muffin tin for a few minutes before transferring them to a wire rack to cool completely.
• While the cupcakes are cooling, prepare the frosting. In a large bowl, beat the softened butter until creamy.
• Gradually add the powdered sugar, alternating with the milk, and mix until smooth and fluffy. Stir in the vanilla extract.
• Once the cupcakes are completely cool, frost them with the vanilla buttercream and sprinkle with extra rainbow sprinkles.