If you have only one pan and a recipe calls for more cupcakes than your pan will make, cover and refrigerate the rest of the batter while baking the first batch. Cool the pan about 15 minutes, then bake the rest of the batter, adding 1 to 2 minutes to the bake time.
Heat oven to 350 degrees F (325 degrees F for dark or nonstick pans). Line two cupcake pans with paper baking cups.
Make the cake batter as directed on the box. Divide the batter evenly among the muffin cups (each cup should be about two-thirds full). Bake as directed on the box. Cool the cupcakes in their pans for 10 minutes then remove them from the pans and place them on a cooling rack. Cool completely, about 30 minutes.
Using melon baller, scoop out the center of each cupcake, about 1 inch deep. Fill each cupcake with 1 heaping teaspoonful of candies.
Spoon the frosting into a medium bowl; stir in enough food color until the desired green color is reached. Frost the cupcakes with the green frosting; sprinkle with colored sugar. Top each cupcake with a yellow PEEPS® chick. Store loosely covered.