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Move over plain ole’ Oatmeal Fudge Bars, there is a new recipe in town and they are about to rock your world. Monster Cookie Oatmeal Fudge Bars have all of the traditional elements with extra special ingredients everyone will go crazy for. Keep scrolling for the recipe and see the fun add-ins!
This recipe is literally the combination of a traditional Oatmeal Fudge Bar with a Monster Cookie. I have been dreaming about it for at least a year and let me tell you something…it was worth the wait.
What is a Monster Cookie?
Monster cookies are a peanut butter cookie that is packed with oats, chocolate chips and M&M’s. They are normally soft, thick and just as addictive as they are delicious.
What are Oatmeal Fudge Bars?
Oatmeal Fudge Bars are a thick oatmeal cookie that has a creamy chocolate layer, followed by another oatmeal cookie layer. The cookie is soft, the center is silky smooth and texture is where it is at.
Disclaimer: This Monster Cookie Oatmeal Fudge Bars Recipe recipe may contain affiliate links and I will receive a small commission from any purchases you may make from these links. It’s one of the ways I support my site.
When combined you have a cookie bar that perfectly marries the two already amazing cookies into one glorious bite!
How to make the Monster Cookie Oatmeal Layer
Begin by combining the butter, peanut butter, brown sugar and vanilla. Brown sugar is the only sugar used and helps to get the compact and soft cookie texture.
Once that is smooth, add the eggs, baking powder and salt.
Finally, add the flour and quick oats but don’t over mix. You want everything combined but the texture should be thick.
Why Quick Oats for your Oatmeal Fudge Bars?
Quick oats are a more finely ground whole oat which makes them more powdery. That consistency helps them to be a great binder in this bar.
Now is where things get fun! The add ins! Mini chocolate chips, peanut butter chips and M&M’s, can either be mixed in by hand or on a low speed with the mixer. You don’t want the M&M’s to break apart.
In a 9×13 pan {sprayed with non-stick spray} add about 60% of the dough in the bottom and press it down. You want it to cover the bottom of the entire pan in an even layer.
How to Make the Fudge Layer
The fudge layer starts with a package of semi-sweet chocolate chips, a can of sweetened condensed milk and butter.
Put it in the microwave for 2 minutes and stir. Add 30 second intervals until smooth.
Pour over the top of the monster cookie dough and spread out evenly.
Take the remaining 40% of the dough and crumble it over the top of the fudge layer. There will be small areas where the fudge layer shows through and that is exactly how it is supposed to be.
Bake in a 350 degree oven for 30-35 minutes or until the top of the bars start to turn golden brown.
It needs to cool completely at room temperature. Once cooled, chill for an hour before cutting them into bars.
Cooling and chilling the bars will help them cut so much easier. The next step just might be my very favorite…the first taste test.
I have not been this excited about a recipe in a very long time. These oatmeal fudge bars are SO delicious and wonderful! Your family and friends will go crazy for them…if they last long enough for them to get a bite.
Do you like these Oatmeal Fudge Bars? Try these…
- Soft & Chewy Easy Chocolate Chip Cookie Bars
- Salted Caramel Butter Cake Bars
- Glazed Lemon Poppy Seed Bars
- Pecan Shortbread Bars
- Blackberry Crumble Bars
- Cranberry Bliss Shortbread Bars

Monster Cookie Oatmeal Bars
Ingredients
- 1 box yellow cake mix, {13.25 ounces}
- ยฝ cup brown sugar, {packed}
- ยฝ cup butter, {melted}
- ยฝ cup peanut butter
- 1 large egg
- ยผ cup milk
- 1 teaspoon vanilla extract
- 1 ยฝ cups quick oats
- ยฝ cup mini chocolate chips
- ยฝ cup M&M's
Instructions
- Preheat the oven to 350ยฐ..
- In a large bowl, combine the yellow cake mix and brown sugar, whisk the ingredients together to remove any lumps. Add the melted butter, peanut butter, egg, milk and vanilla to the dry ingredients and mix using an electric mixer. Add the quick oats and mix until evenly distributed. Finally, add the chocolate chips and M&M's to the cookie dough and mix.
- Prepare a 9x9 baking pan by spraying it liberally with nonstick cooking spray {or line with parchment paper}. Add the cookie dough to the prepared pan and spread out into an even layer.
- Bake for 30-35 minutes or until the top is golden brown. Remove from the oven and let the cookie bars cool completely in the pan before slicing into squares. Serve and enjoy. Store leftovers in an airtight container at room temperature for up to 4 days.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.



























These were so decadent and easy to make!
A top article to read. Thanks a lot for sharing this. Fine work. Keep it up.