In a medium bowl, sift the flour, baking soda, and salt. Set aside.
2 cups All-purpose flour, 1 teaspoon Baking soda, 1 teaspoon Salt
Using a mixer, beat the melted butter (make sure it is cooled to room temperature before using), brown sugar, and sugar. Beat on high speed for 2 minutes. It will become pale in color.
1 cup Unsalted butter, 1 cup Brown sugar, 1 cup White granulated sugar
Add the vanilla, peanut butter, and eggs. Mix on medium until combined. Add the dry ingredients and mix on low speed.
1 teaspoon Pure vanilla extract, 1 cup Peanut butter, 2 Large eggs
Take off the mixer. Add the muddy buddies and gently fold it in using a rubber spatula.
1 ½ cups Muddy Buddies
Preheat the oven to 350°F. Line two cookie sheets with parchment paper. Let the cookie dough sit for 10 minutes for the flour to absorb into the dough.
Scoop using a 2 tablespoon or 2 oz cookie scoop. Scoop 6 cookie dough balls per cookie sheet. Roll each cookie dough ball into the sparkling sugar. Place on the cookie sheet and slightly press on the dough balls to flatten them.
Sparkle sugar
Bake 1 cookie sheet at a time. Bake for 12-14 minutes until the edges of the cookie are lightly golden brown. While warm, top immediately with extra muddy bubby pieces.
Let the cookies sit on the hot pan for 5 minutes before transferring to a cooling rack.