Soft & Chewy M&M Cookies

½ cup (1 stick) Unsalted Butter, softened ½ cup Light Brown Sugar, packed ¼ cup Granulated Sugar 1 large Egg 2 teaspoons Vanilla Extract 1 ¼ cup All-Purpose Flour ¼ cup Instant Vanilla Pudding Mix ½ teaspoon Baking Soda ¼ teaspoon Salt, or to taste ¾ cup M&Ms, more to add to dough mounds ½…