Make the Sugar Cookies:

1. Preheat the oven to 350ºF.
2. Add 60 grams of Lucky Charms cereal with the marshmallows removed to a food processor and grind to a fine powder.
3. In a medium-sized bowl, combine the Lucky Charms cereal powder, flour, baking soda, baking powder, and salt.
4. In a separate large bowl, cream the butter and sugar until lighter in color. 
5. Add the egg and vanilla. Beat until light and fluffy. 
6. Add the dry ingredients and mix to combine.
7. Make roughly 2-inch cookie dough balls, set a few inches apart on a cookie sheet, and bake for 10-12 minutes or until  starting to turn lightly golden brown on the edges. 

Make the Frosting and Crumbled Cereal Topping:

1. Soak around 1/2 cup of Lucky Charms cereal and 1/2 cup of milk together in a small bowl. Set aside and allow to infuse for at least 20 minutes, stirring a couple times in between. 
2. In a medium-sized bowl, beat the butter for 1 minute.
3. Add the powdered sugar, vanilla extract, and salt. Beat again until smooth. 
4. Take 2 tablespoons of milk from the soaking cereal bowl and add to the frosting mixture. Beat until light and fluffy. Set aside. 
5. Separate the marshmallows from about 1/2 cup of Lucky Charms. Roughly crush the separated marshmallows.
6. In a skillet over medium heat, toast the remaining cereal (without marshmallows) with the extra 1/2 tablespoon of butter until golden brown. 
7. Crush the toasted cereal roughly into the bowl with the crushed marshmallows and toss together. 

Assemble the Final Cookies:

1. Add the frosting to a ziplock or piping bag with the tip cut off (roughly 1-centimeter diameter opening). 
2. Pipe a swirl of frosting on each cookie, starting in the middle of the cookie and moving outward.
3. Sprinkle with the toasted and crushed Lucky Charms.