Preheat oven to 350 degrees F. Line muffin tin with 12 cupcake liners.
Combine flour, baking soda, baking powder, and salt in a medium bowl.
Melt better in a large microwave safe bowl. Whisk in sugar.
Stir in egg, yogurt, milk, and vanilla.
Gradually stir in flour mixture. Gently fold in sprinkles.
Divide batter between 12 liners (Fill around ⅔ of the way full). Bake for 20 minutes or until a toothpick inserted in the center comes out clean. Cool completely.
For the Frosting
Beat softened butter for 3-4 minutes. No electric mixer? No problem, just use a wooden spoon.
Stir in heavy cream, and vanilla. Gradually stir in confectioner's sugar until you reach your desired consistency.
Spread or pipe frosting onto cupcakes. Top with additional sprinkles if desired.