The Best Thick, Chewy, Soft-Baked M&M Cookies

INGREDIENTS

12 tbsp

butter, melted & cooled to room temperature ((I use salted))

3/4 cup

brown sugar

1/2 cup

granulated sugar

large egg

large egg yolk

1 tsp

vanilla extract

2 cups

+ 2 tablespoons all-purpose flour

1 tsp

baking soda

1/2 tsp

salt

1 cup

miniature m&m's ((plus additional for tops of cookies))