Monster Cookie Bars

Monster Cookie Bars are everything you could want - soft, chewy, extra thick and filled with peanut butter, oatmeal, chocolate chips and M&Ms. It's an easy cookie bar recipe that's faster than making a batch of cookies and impossible to resist.

Course Dessert

Cuisine American

Keyword Monster Cookie Bars, Monster Cookies

Prep Time 15

Cook Time 30

Total Time 45

Servings squares

Calories 359kcal

Author Fiona Dowling

Equipment

9x13 inch (23 x 33 cm) baking pan*

Ingredients

¾ cup unsalted butter (168 grams) softened
1 cup brown sugar (210 grams)
½ cup granulated sugar (100 grams)
¾ cup smooth peanut butter not natural
2 large eggs
1 tablespoon vanilla extract
1 ⅔ cups all-purpose flour (208 grams)
1 teaspoon baking soda
¼ teaspoon salt
1 ½ cups old-fashioned oats
¾ cup chocolate chips your favorite variety
¾ cup M&Ms

Instructions

Preheat the oven to 350F degrees. Line a 9x13 inch pan with parchment paper so there's a 1 to 2-inch overhang on all sides, or lightly grease.
In a large bowl beat the butter, brown sugar, granulated sugar and peanut butter until you no longer see clumps of butter or brown sugar.
Mix in the eggs and vanilla to the butter mixture until smooth and creamy.
Turn the mixer down to low speed and mix in the flour, baking soda & salt.
Stir in the oats. I do this by hand.
Turn off the mixer and stir in the chocolate chips and M&Ms.
Spoon the dough into the prepared pan and smooth into an even layer using an angled spatula. Alternatively, press it down into an even layer with lightly greased fingers.
Bake for about 30-35 minutes or until the top looks golden and the bars are starting to pull away from the edges of the pan. The bake time will vary depending on your oven and how gooey you like your bars.
Cool the bars in the pan for at least 40 minutes - if you only cool the bars for 40 minutes they will be very gooey when you slice in. If you lined the pan with parchment, lift them out of the pan using the overhang and place on a cutting board. Then slice using a sharp knife.

Notes

Butter: If using salted butter, you can omit the salt from the recipe.
Peanut Butter: Be sure to use smooth, commercially prepared peanut butter. I do not recommend using anything labeled natural or where the oil sits on top. These peanut butters (while delicious) can lead to inconsistent results due to different amounts of oil being added.
Oats: I recommend using large, rolled oats as opposed to quick oats. Quick oats will work but don't provide the same amount of texture. Make sure to use rolled oats - not steal cut oats. Instant oats do not provide enough texture and behave more like flour instead of oats.
M&Ms: I prefer to use regular instead of peanut butter because peanut M&Ms make the bars harder to slice.
Storage: Store cooled bars in an airtight container at room temperature for up to 4 days. Baked and cooled bars can be frozen for up to 2 months, then thaw in the fridge.
Nutrition: Nutrition details provided are an estimate only and based on 1 bar, assuming the bar is sliced into 18 equal bars.

Nutrition