In a mixing bowl, combine 2 cups of all-purpose flour, 1/2 teaspoon of salt, 1 teaspoon of baking soda, and a generous sprinkle of colorful sprinkles. Whisk until evenly mixed.

In a separate bowl, cream together 1 cup of butter and 3/4 cup each of brown and granulated sugar. Beat for 3-5 minutes until light and fluffy. Add 1 egg and 2 teaspoons of vanilla extract, mixing well.

Gradually fold the dry ingredients into the wet ingredients until no flour is visible.

Shape the dough into a ball, wrap in plastic wrap, and refrigerate for at least 1 hour.

Preheat your oven to 325°F (160°C) and line your baking sheets with parchment paper.

Scoop dough portions onto prepared baking sheets, flatten slightly, and bake for 8-10 minutes.

Cool cookies for 5 minutes on the baking sheets, then transfer to a cooling rack.

Whisk together 2 cups of icing sugar, 1/4 cup of softened butter, 2 tablespoons of milk, and 1 teaspoon of vanilla until smooth.

Frost cooled cookies and top with Lucky Charms marshmallows.