For the Cereal Milk:

1. Combine milk and Lucky Charms cereal in a medium bowl. Let sit for 30 minutes, stirring occasionally.
2. Strain the milk through a fine mesh sieve to remove the cereal, and set aside the cereal milk.

For the Cereal Milk Cupcakes:

1. Preheat the oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners.
2. In a medium bowl, whisk together flour, baking powder, salt, cinnamon, and nutmeg. Set aside.
3. In a large bowl, cream together the butter and sugar until light and fluffy. Add vegetable oil, eggs, and vanilla, mixing until smooth.
4. Gradually add the dry ingredients to the wet ingredients, alternating with the cereal milk. Mix until just combined.
5. Fill each cupcake liner about 2/3 full with batter and bake for 18-20 minutes. Cool completely before filling and frosting.

For the Marshmallow Filling:

1. Beat butter and powdered sugar together until smooth.
2. Add marshmallow creme and beat until fully incorporated.
3. Gently fold in Lucky Charms marshmallow pieces and chopped cereal.

For the Vanilla Frosting:

1. Beat butter and shortening together until smooth.
2. Gradually add powdered sugar, one cup at a time, and continue beating until fluffy.
3. Add vanilla extract and salt, mixing until well combined.

Assembling the Cupcakes:

1. Once cupcakes are cool, use a small knife or corer to create a well in the center of each cupcake.
2. Fill the cupcakes with marshmallow filling.
3. Frost with vanilla frosting and top with extra Lucky Charms marshmallows and chopped cereal.