Monster Cookie Bars

5 from 5 votes

When it comes to bringing a dessert to a party I love bringing a bar cookie. Not only are they a cinch to throw together but nobody can resist them. Especially a cookie bar like this thick, chewy oatmeal one made with peanut butter, and chock full of chocolate chips and chocolate candies.

Prep Time15

Cook Time25

Total Time40

Course: Dessert

Cuisine: American

Servings: bars

Calories: 471kcal

Author: Heather Perine

Ingredients

1 ½ cups (180 g) all purpose flour *spooned and leveled
2 cups (198 g) old fashioned oats *see note
1 teaspoon baking powder
1 teaspoon baking soda
½ teaspoon salt
1 cups (213 g) packed light brown sugar
1/2 cup (100 g) granulated white sugar
1 cup (2 sticks, 226 g) unsalted butter softened
2 large eggs room temperature
2 teaspoons vanilla extract
½ cup (135 g) smooth peanut butter
1 cup (170 g) semi-sweet chocolate chips
1 cup (170 g) candies (I used a combination of peanut butter cups and M&Ms)

Instructions

Preheat and prepare pan. Preheat oven to 350°F. Grease or line a 9x13 baking pan with parchment paper.
Whisk dry ingredients together. In a mixing bowl, whisk together the flour, oats, baking powder, baking soda and salt. Set the bowl aside. 1 ½ cups (180 g) all purpose flour 2 cups (198 g) old fashioned oats 1 teaspoon baking powder 1 teaspoon baking soda ½ teaspoon salt
Cream butter and sugar. In a large mixing bowl, cream softened butter and sugars together until light and fluffy. Beat in eggs one at a time, scraping down bowl as needed. Beat in vanilla and peanut butter until combined. 1 cup (2 sticks, 226 g) unsalted butter 1 cups (213 g) packed light brown sugar 1/2 cup (100 g) granulated white sugar 2 large eggs 2 teaspoons vanilla extract ½ cup (135 g) smooth peanut butter
Add flour mixture and chips. Stir in the flour mixture just until combined. Fold in chocolate chips and candies. 1 cup (170 g) semi-sweet chocolate chips 1 cup (170 g) candies
Bake. Spread the batter into prepared pan and bake for about 25 minutes just until the edges are golden brown and set. The center of the bars will still be slightly soft. Remove the bars from the oven and allow to cool completely and the center is set. Once the bars have cooled, remove from the pan and cut into squares.

Notes

Storage: These monster cookies can be stored in an airtight container at room temperature for up to 3 days. They can also be stored in the freezer for up to 3 months.
Make Ahead: Yes, you can make the bars ahead of time. Just bake the monster cookie bars according to the recipe, then let them cool completely. Once the monster cookie bars are cool, wrap them tightly in plastic wrap and store them in the refrigerator for up to 3 days or in the freezer for up to 3 months. When you are ready to serve the bars, thaw them overnight in the refrigerator or at room temperature for 30-60 minutes.
Substitution Tip: You could make these into cookies. Using a 1 ½-inch cookie scoop, scoop cookies onto baking sheet and bake for 10-12 minutes until edges are golden brown, and middles are set.
Oats: I recommend using old fashioned oats because of their larger heartier texture. But you can swap and use quick oats. Quick oats are a bit more broken down and dustier in my opinion to use.
Peanut Butter: I like to use a smooth creamy peanut butter for these bars. I don't recommend using a natural peanut butter because it can be a bit oilier in texture. I usually use Jif or Skippy. You could swap and use a chunky peanut butter for a bit of extra crunch in these cookie bars!
Chocolate Chips: I used regular semi-sweet chocolate chips, but you could use chocolate chunks or mini sweet chocolate chips. You could also use chopped chocolate. And if you wanted more chocolate flavor then stir in some peanut butter chips or try swapping and using white chocolate chips.
Candies: Traditionally a monster cookie bar uses colorful m&m candies stirred in. But you could easily swap and use Reese's Pieces or another favorite candy! I also stirred in chopped peanut butter cups as well.I love to around the holidays use Christmas M&M's and stir in white chocolate chips for a fun festive Christmas cookie bar

Nutrition