Step 1

Preheat oven to 350 degrees F. Line a 12-cup muffin pan with cupcake liners. Set aside.

Step 2

Whisk gluten-free flour, sugar, baking powder, and salt in a medium bowl. Add milk, eggs, oil, and vanilla extract. Mix until the batter is smooth.

Step 3

Spoon the batter into the cupcake liners. Fill each cup 2/3 full. This prevents overflow during baking. Bake until a toothpick inserted in the center of the cupcake comes out clean, about 18 minutes.

Step 4

Allow cupcakes to cool in the pan for five minutes. Then transfer to a wire rack to cool completely. Frost cupcakes when cool.

Step 5

Store cupcakes, tightly covered, on the counter for up to three days or freeze for up to two months.

Step 6

Beat butter until smooth in a medium bowl. Add powdered sugar, milk, and vanilla extract. Turn mixer to medium-low speed. Mix. Increase speed to medium-high and beat until light. If frosting is too thick, add more milk.