Preheat your oven according to the cupcake temperature listed on your cake mix box and lightly coat the inside of 16 to 20 eight-ounce glass jars with non-stick cooking spray.

Prepare the cake batter in a large bowl by following the instructions provided on the cake mix box.

Pour the batter into the prepared jars, filling each one about halfway full, and wipe away any drips from the rims to ensure a clean finish.

Arrange the jars on baking sheets so they are not touching and bake for the time suggested for cupcakes on the box, adding about 5 minutes as needed until a toothpick inserted into the center comes out clean.

Allow the jars to cool completely on a wire rack before adding any frosting.

Prepare the frosting by beating the softened butter with an electric mixer until creamy, then gradually mix in the confectioners sugar, milk, and vanilla until the texture is light and fluffy.

Divide the frosting into two separate bowls and stir in your chosen food coloring until you reach the desired shades.

To assemble, either pipe frosting directly onto the cooled cake or scoop out a portion of the cake to create a hidden layer of frosting in the middle before topping with more frosting and sprinkles.