1. To make the cereal milk, add the milk and Lucky Charms to a bowl and let sit for 20 minutes. Strain the milk and discard the cereal. You’ll have a little more milk than you need for the cupcakes, so set the extra aside for the frosting.
2. To make the cupcakes, prepare a cupcake pan with cupcake liners and preheat the oven to 350°F (176°C).
3. Combine the flour, baking powder and salt in a medium sized bowl and set aside.
4. Add the butter, sugar and oil to a large mixer bowl and beat together until light in color and fluffy, about 3 minutes. Do not skimp on the creaming time. You should see a noticeable change in the color and texture of the mixture – light and fluffy.
5. Add the eggs one at a time, mixing until mostly combined after each. Add the vanilla extract with the second egg. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
6. Add half of the dry ingredients to the batter and mix until mostly combined.
7. Slowly add the cereal milk and mix until well combined. The batter might look a little curdled, but that’s ok.
8. Add the remaining dry ingredients and mix until well combined and smooth. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated. Do not over mix the batter.
9. Fill the cupcake liners about 3/4 full and bake for 14-16 minutes or until a toothpick inserted into the center comes out clean.
10. Remove cupcakes from the oven and place on a cooling rack to cool.
11. To make the filling, add the butter to a mixer bowl and beat until smooth.
12. Add about half of the powdered sugar and mix until well combined and smooth. It may take a few minutes to incorporate, but it will.
13. Add the remaining powdered sugar and mix until well combined and smooth.
14. Add the marshmallow cream and stir until well combined.
15. Gently fold in the Lucky Charms marshmallows.
16. To fill the cupcakes, cut out the centers of the cupcakes. You can use a cupcake corer or a knife.
17. Fill the centers of the cupcakes with the filling, then spread some additional filling over the top of the cupcake in a thin layer. You don’t need much on top.
18. Turn the cupcake over and press it into a bowl of the chopped up Lucky Charms cereal. Set cupcakes aside.
19. To make the frosting, add the butter and shortening to a mixer bowl and beat until well combined.
20. Add about half of the powdered sugar and mix until well combined and smooth.
21. Add the vanilla extract and salt and mix until well combined.
22. Add the remaining powdered sugar and mix until well combined and smooth. Add some of the left over cereal milk, as needed for the right consistency.
23. Pipe the frosting onto the cupcakes, leaving the edges of the cupcakes exposed, so you can see the Lucky Charms cereal. Top each cupcake with a Lucky Charms cereal marshmallow.
24. Cupcakes are best if served the same day, so the cereal doesn’t get too soft, but will stay moist and tasty for 2-3 days.