Preheat your oven to 325 degrees F. This is a crucial step, as a well-heated oven ensures even baking.
Line cupcake pans with 24 cupcake liners. Choose fun colors or patterns to make your cupcakes even brighter.
In a large mixing bowl, combine the dry ingredients: the cake mix, sugar, and flour. Mix them well until they're evenly combined.
Add in the wet ingredients: water, eggs, vanilla extract, and sour cream. Using an electric mixer, mix the batter on medium speed for about two minutes until it's smooth and well combined.
Scoop the batter into the cupcake liners. Fill them about two-thirds full to allow room for rising.
Place the cupcake pans in the oven. Bake for 15 to 20 minutes. Keep an eye on them; they’re done when the center springs back when touched and a toothpick comes out clean.
Once baked, remove the cupcakes from the oven and allow them to cool completely on cooling racks. This is essential to prevent the frosting from melting.
In a clean mixing bowl, beat the butter until it's light and fluffy. This will create a great base for your frosting.
Add the powdered sugar and a pinch of salt, mixing well to combine. Gradually add the second vanilla extract and whipping cream, continuing to mix on medium speed for about two minutes, or until smooth.
If desired, add food coloring to the frosting, mixing until you achieve your preferred shade.
Once the cupcakes are completely cool, frost them generously with your delicious buttercream.
Top each cupcake with Marshmallow Peeps, sprinkles, and any additional candy eggs or jelly beans to finish off your delightful creations.
