Preheat your oven to 350℉ and line your baking sheets.
In a bowl (stand mixer makes it easy), beat the butter and both sugars together until fluffy.
¾ Cup Butter, ½ Cup White Sugar, ½ Cup Brown Sugar
Add in the egg and vanilla and beat to mix well.
1 Egg, 1 Tbsp Vanilla Extract
In another bowl, mix together the flour, salt, and baking soda. Add this to the sugar mixture and mix until it comes together into a dough.
½ Tsp Salt, 1 Tsp Baking Soda, 2 Cups Flour
Mix in the cereal marshmallows until evenly distributed.
1 Cup Cereal Marshmallows
Scoop about 1½ tablespoons of dough at a time into balls and arrange them on your baking sheet, 1-2 inches apart from one another to account for spreading as they bake.
Bake each batch of cookies for 9-10 minutes. You want the edges of the cookies to be set but not browning much. When done, remove and let them cool on the baking sheet for about five minutes, and then another ten on a cooling rack. Enjoy!