Adapted from Cook's Illustrated
14 tablespoons butter
1/2 cup sugar
3/4 cup dark brown sugar
2 teaspoons vanilla
1 egg yolk
1/2 teaspoon salt
1/2 teaspoon baking soda
1 3/4 cup flour
1 1/4 cups mini M&M's
1 3.14 ounce bag of M&M's, optional garnish
Preheat oven to 375º.
Melt 10 tablespoons of the butter in a saucepan over medium high heat till melted. Continue cooking a couple more minutes till butter is golden brown with a nutty fragrance. Pour into heatproof bowl, and add the remaining 4 tablespoons of butter. Stir till melted.
Add sugars, then vanilla. Mix in egg and egg yolk. Add baking soda, then flour and mix till just combined. Add M&M's.
Use 4 tablespoon a 1 tablespoon scoop to make dough balls. Place about 2 inches apart on parchment lined cookie sheets. Bake about 10 minutes or till cookies are golden. Press a few regular M&M's into warm cookies to garnish. Cool on rack.
Makes approximately 24 cookies.