Preheat your oven to 350°Fahrenheit and line a baking sheet with parchment paper.
In a stand mixer or in a large bowl with a hand held mixer, combine the butter with the granulated sugar and light brown sugar until light and fluffy.
Add in the egg and vanilla extract and combine once more. You might need to scrape down the sides of the bowl so everything is getting mixed!
Stir in the dry ingredients and mix until a dough begins to form, then stir in the lucky charms marshmallows.
Using a medium cookie scoop, or a tablespoon, scoop out 1 ½ tablespoons of cookie dough. Place on the baking sheet so they’re 3-4 inches apart.
Bake the cookies for 8-11 minutes. The edges should look set but the cookies should not be golden brown - the tops may look a little under-baked. Let them cool on the baking sheet for 5 minutes before removing to a wire cooling rack to cool completely.
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Notes
Measuring Flour: Properly measure your flour using either a kitchen scale or by fluffing it up in the bag with a fork, then using a spoon to scoop the flour into the measuring cup and then use the back of a butterknife to level it off (the is the scoop and level method)Butter: if necessary, butter can be replaced with coconut oil (solid at room temperature, not melted)White Chocolate Chips: Feel free to add half a cup of white chocolate chips if desired. Note that this does make the cookies much sweeter.Storage and Freezing:Store the cookies in an airtight container or ziploc bag at room temperature for 5-6 days.The baked cookies can be frozen in a freezer bag for up to 2 months. Thaw at room temperature when you're ready to eat them.