Preheat the oven to 350 degrees and line a baking sheet with parchment paper.

Place the Lucky Charms in a food processor blender and blend until a fine powder. Set aside.

Beat together the butter and sugars until smooth and well combined.

Add the egg and vanilla and beat to mix.

Add the flour, blended cereal, salt, and baking soda to the bowl. Beat to mix.

Fold in the mini marshmallows.

Scoop the dough into balls and place the dough balls on the prepared baking sheet, making sure the mini marshmallows aren’t touching the pan on the sides to keep them from melting.

Press more Lucky Charms cereal into the tops of the cookies.

Bake for 10 to 12 minutes, until the edges are just beginning to brown but the centers are still soft. Allow to cool on the pan for 5 minutes, then transfer to a wire cooling rack to cool completely.