If you’re on the lookout for a delightful treat that combines the chewy goodness of oatmeal cookies with the indulgence of chocolate, then look no further! These Monster Oatmeal Chocolate Chip Cookie Bars are the perfect solution for satisfying your sweet tooth while also being a crowd-pleaser. With a thick, chewy texture and a delicious blend of flavors, these bars are not only easy to make but also perfect for sharing at parties, potlucks, or simply enjoying at home with family.
Why It’s Crowd-Pleasing

These Monster Oatmeal Chocolate Chip Cookie Bars are incredibly versatile. They combine classic ingredients that everyone loves—oats, chocolate chips, and a bit of crunch from the addition of Reese’s Pieces or M&Ms. Each bite is packed with flavor and texture, making them a hit with kids and adults alike. Plus, they’re simple to whip up, meaning you can have a pan of these delicious bars ready in no time. Whether you’re celebrating a special occasion or just want a delicious snack, these bars are sure to impress!
Your Shopping Guide
To make these mouthwatering Monster Oatmeal Chocolate Chip Cookie Bars, here’s a comprehensive list of what you’ll need:
- 2 ½ cups old fashioned oats
- 2 cups all-purpose flour
- 1 cup brown sugar, packed
- ½ cup granulated sugar
- 1 teaspoon baking soda
- 1 teaspoon salt
- 1 cup canola oil
- 2 large eggs
- 1 tablespoon vanilla extract
- 1 ½ cups semi-sweet chocolate chips
- ½ cup Reese’s Pieces or M&Ms
With these ingredients in hand, you are well on your way to creating a delicious dessert that everyone will love!
Tools of the Trade
Before you start baking, gather the necessary tools to make the process seamless:
- Mixing bowls: To combine the wet and dry ingredients.
- Measuring cups and spoons: For precise measurements of each ingredient.
- Spatula: To mix everything together and transfer the batter to the baking pan.
- Baking pan (9×13 inch): The perfect size for these cookie bars.
- Parchment paper: For lining the pan, making cleanup easy.
Make Monster Oatmeal Chocolate Chip Cookie Bars: A Simple Method

Ready to bake? Follow these simple steps to create your own Monster Oatmeal Chocolate Chip Cookie Bars!
Step 1: Preheat the Oven
Preheat your oven to 350°F (175°C). This ensures that your bars bake evenly and develop that perfect golden color.
Step 2: Prepare the Baking Pan
Line a 9×13 inch baking pan with parchment paper, leaving some overhang for easy removal later.
Step 3: Combine Dry Ingredients
In a large mixing bowl, whisk together the old fashioned oats, all-purpose flour, brown sugar, granulated sugar, baking soda, and salt until well combined.
Step 4: Mix Wet Ingredients
In another bowl, whisk together the canola oil, eggs, and vanilla extract until the mixture is smooth and well blended.
Step 5: Combine the Mixtures
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; a few lumps are okay!
Step 6: Add Chocolate Chips
Fold in the semi-sweet chocolate chips and your choice of Reese’s Pieces or M&Ms. This is where the fun comes in—feel free to customize with your favorite candies!
Step 7: Bake
Spread the batter evenly into the prepared baking pan and smooth the top with a spatula. Bake in the preheated oven for 25-30 minutes or until the edges are golden brown and a toothpick inserted in the center comes out clean.
Step 8: Cool and Slice
Once baked, remove the pan from the oven and let it cool completely in the pan. Once cooled, use the parchment paper to lift the bars out of the pan. Cut into squares or rectangles and serve!
Make It Year-Round

These Monster Oatmeal Chocolate Chip Cookie Bars are perfect for any season. Here are some ways to enjoy them throughout the year:
- Fall: Add a dash of cinnamon or pumpkin spice for a seasonal twist.
- Winter: Mix in some chopped nuts or dried fruit for added texture and flavor.
- Spring: Experiment with pastel-colored candies like Easter M&Ms for a festive touch.
- Summer: Serve them with a scoop of ice cream for a delicious dessert treat on hot days.
Behind-the-Scenes Notes
These Monster Oatmeal Chocolate Chip Cookie Bars are not just delicious, but also flexible. Here are a few notes to keep in mind while preparing them:
- Substituting the canola oil with melted coconut oil can give a subtle tropical flavor.
- If you prefer a healthier option, consider using whole wheat flour instead of all-purpose flour.
- Store the bars in an airtight container to keep them fresh for up to a week.
Make Ahead Like a Pro
If you’re planning for a gathering or simply want to have these bars on hand, here are some tips for making them ahead of time:
- Prepare the batter and store it in the refrigerator for up to 24 hours before baking.
- Bake the bars ahead of time and freeze them for up to three months. Just thaw them in the fridge overnight before serving.
- Cut the bars into squares and individually wrap them for easy grab-and-go snacks!
Quick Questions
Can I use quick oats instead of old fashioned oats?
While quick oats can be used, they will produce a different texture. Old fashioned oats provide a chewier bite, which is ideal for these cookie bars.
What can I substitute for the chocolate chips?
If you’re looking for alternatives, you can use white chocolate chips, butterscotch chips, or even chopped chocolate bars. For a healthier option, consider dark chocolate chips.
How should I store these cookie bars?
Store the Monster Oatmeal Chocolate Chip Cookie Bars in an airtight container at room temperature for up to a week, or in the refrigerator for longer freshness.
Can I make these vegan?
Yes! You can replace the eggs with flax eggs (1 tablespoon ground flaxseed mixed with 2.5 tablespoons water for each egg) and use a vegetable oil instead of canola oil.
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In Closing
These Monster Oatmeal Chocolate Chip Cookie Bars are a delightful blend of flavors and textures, making them an irresistible treat for any occasion. With a straightforward recipe and the flexibility to customize them, they can become a staple in your baking repertoire. So gather your ingredients, follow the steps, and indulge in the joy of baking these delicious bars. Enjoy every gooey, chocolatey bite!

Monster Oatmeal Chocolate Chip Cookie Bars.
Ingredients
Equipment
Method
- Step 1: Preheat your oven to 350°F (175°C).
- Step 2: Line a 9x13 inch baking pan with parchment paper.
- Step 3: In a large mixing bowl, whisk together the oats, flour, brown sugar, granulated sugar, baking soda, and salt.
- Step 4: In another bowl, whisk together the canola oil, eggs, and vanilla extract.
- Step 5: Pour the wet ingredients into the dry ingredients and stir until just combined.
- Step 6: Fold in the chocolate chips and Reese’s Pieces or M&Ms.
- Step 7: Spread the batter into the prepared pan and bake for 25-30 minutes.
- Step 8: Let cool completely before lifting out and slicing into bars.
Notes
- Substitute canola oil with melted coconut oil for a tropical flavor.
- Use whole wheat flour for a healthier option.
- Store in an airtight container for up to a week.
