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Loaded Oatmeal Cookie Bars marry blondies and oatmeal cookies – clean out your pantry and fill the cookie bars with your favorite things!

Although these oatmeal bar cookies stay chewy for days, they probably won’t last you that long. Too delicious to store away, you’ll want to finish every bite left! 

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stacked oatmeal bars with m&ms baked in

Since I’m sharing multiple variations from this one cookie bar recipe, you can enjoy this treat  any time of day. Who said sweets are only for dessert? I love to wake up to a warm, oatmeal cookie bar to compliment my morning coffee. 

Bar cookies are just so much easier to make – just press them in the pan and bake. No need to chill dough, no need to worry about if they’ll spread too much. And if you’re like me and line the pan with foil, there is almost no clean up! #barcookiesforthewin

Why you’ll love this recipe

The best part about this oatmeal bar recipe are the mix-ins. You can add whatever you want! It’s an easy way to clean out your pantry, just throw in 2 cups total of any add-ins. 

  • Chocolate chips (white, semi-sweet, or milk)
  • Butterscotch chips
  • Peanut Butter chips
  • Toffee bits
  • M&Ms or Reese’s Pieces
  • Chopped up candy bars like Butterfingers or Reese’s Peanut Butter Cups
  • Coconut flakes
  • Nuts 
stacked oatmeal bars with m&ms baked in

Ingredients in Oatmeal Bar Cookies

  • Unsalted butter: softened
  • Brown sugar: packed
  • Egg: I use large eggs 
  • Vanilla extract: to bring out the flavor 
  • Salt: just a pinch to enhance flavor
  • Baking soda: for leavening
  • Cinnamon: a must when using oats in your recipe
  • All-purpose flour: be sure to use the right amount
  • Quick Cooking Oats: you can also use old-fashioned oats 
  • Mix-ins: 2 cups of any add-ins you want!

Remember when I said this oatmeal cookie bar recipe is easier than baking cookies? Since you don’t have to worry about any spreading or chilling dough, all you really do is just mix the ingredients and slap it all in a pan to bake. It’s really that simple! 

  1. Prepare- preheat the oven to 350°F. Line the pan with foil and spray with cooking spray.
  2. Mix- cream the brown sugar and butter in the bowl. Beat the eggs and vanilla until combined. Mix the salt, baking soda, cinnamon, flour and mix until combined. Stir in oats and your mix-ins
  3. Transfer the dough into the prepared pan 
  4. Bake for about 25 minutes. Then, let it cool completely before slicing into squares 
  5. Store in an airtight container for up to 4 days or freeze for up to 2 months!
stacked oatmeal bars with m&ms baked in

Variations

Luckily for you, this one cookie bar recipe has endless variations. Since you can add any mix-ins you want, you can save this recipe as your go-to treat and play around with different variations for each occasion or mood. 

Here are a few of my favorite ways to compliment an occasion with this one oatmeal cookie bar recipe: 

  • Add your favorite chocolate pieces. White, dark, milk or semi sweet chocolate 
  • You can’t ever go wrong with cinnamon raisin! 
  • Add colorful fun with m&ms!
  • Get the best of all worlds with a trail mix of pretzels, chocolate chips, granola, dried fruit and more! 
  • Add some chocolate covered espresso beans to the mix for a crunchy kick of caffeine! 

Get creative and add in whatever your heart desires at the moment. I love how this recipe is so easy to tailor to your mood. 

FAQs

How long do you bake oatmeal cookie bars?

Bake for about 25 minutes. The center should be jiggly when they come out. It will finish baking as it cools. 

Can you freeze oatmeal cookie bars?

Yes, you can! Freeze for up to 2 months and your oatmeal cookie bar will still be just as chewy good!

How do you know when oatmeal cookies are done?

Getting close to the 25 minute mark, you should see the edge brown and rise to a crisp. The center should still be soft and jiggly. Remove to finish baking while it cools. 

Have You Made This Recipe?

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stacked oatmeal bars with m&ms baked in

Loaded Oatmeal Blondies

5 from 6 votes
Oatmeal Cookie Bars filled with anything you like – this is the perfect recipe to clean out your baking cabinet!
Prep Time 15 minutes
Cook Time 25 minutes
Total Time 40 minutes
Yield 24 bars
Serving Size 1 bar

Ingredients
 

  • ½ cup (113g) unsalted butter , softened
  • 1 ¼ cups (250g) packed brown sugar
  • 1 large egg
  • 1 teaspoon vanilla extract
  • ½ teaspoon salt
  • ½ teaspoon baking soda
  • 1 teaspoon cinnamon
  • 1 cup (124g) all-purpose flour
  • 1 ½ cups Quick Cooking Oats
  • 2 cups of mix-ins (see note)

Instructions

  • Preheat oven to 350°F. Line a 9×13” pan with foil and spray with cooking spray. (Foil is optional; I like using it for easy removal.)
  • Cream brown sugar and butter in the bowl of an electric mixer fitted with a paddle attachment. Add eggs and vanilla and beat until combined. Mix in salt, baking soda, and cinnamon. Add flour and mix until combined. Stir in oats. Stir in your mix-ins.
  • Press into prepared pan (dough is sticky, spray your hands with cooking spray to avoid it sticking to your hands). If you want, you can sprinkle a few more of your mix-ins on the top to make them look prettier (as I did with the mini M&Ms in the pictures).
  • Bake for about 25 minutes. (Be careful not to overcook – the center will still be jiggly when you take these out of the oven and they will finish cooking and firming up as they cool.) Cool completely before slicing into squares.
  • Store in an airtight container for up to 4 days or freeze for up to 2 months.

Recipe Notes

Mix-Ins: Use anything you want! Just make sure to use 2 cups total of whatever you choose. Here are some ideas:
  • Chocolate Chips (White, milk, semi-sweet)
  • Butterscotch or peanut butter chips
  • M&Ms or Reese’s Pieces
  • Toffee Bits
  • Butterfinger Bits
  • Chopped Nuts
  • Chopped peanut butter cups
  • Shredded Sweetened Coconut

Recipe Nutrition

Serving: 1bar | Calories: 194kcal | Carbohydrates: 28g | Protein: 2g | Fat: 9g | Saturated Fat: 5g | Polyunsaturated Fat: 0.3g | Monounsaturated Fat: 1g | Trans Fat: 0.2g | Cholesterol: 18mg | Sodium: 78mg | Potassium: 86mg | Fiber: 1g | Sugar: 20g | Vitamin A: 130IU | Vitamin C: 0.003mg | Calcium: 27mg | Iron: 1mg
Nutritional information not guaranteed to be accurate
Course Dessert
Cuisine American

Other Favorite Oatmeal Cookies:

Easy Oatmeal Cookie Bars – these are loaded oatmeal blondies – add anything you like – we call these kitchen sink cookies!

Last Updated on January 24, 2023

Dorothy Kern

Welcome to Crazy for Crust, where I share recipes that are sometimes crazy, often with a crust, and always served with a slice of life.

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47 Comments

  1. I loved this recipe. I did overbake a bit by accident but I loved the bars anyway. They just were a little more crunchy than they should have been but they tasted terrific. If I make again, I will pay better attention- lol.

  2. These are AMAZING! I had a blondie/oat craving and this popped up. I used toasted coconut, chocolate chips, and toffee bits because that was what I had on hand. I brought the rest in to work and am now required to bring them for all meetings/potlucks 😂 Excellent recipe! I’m trying a vegan version using Earth Balance, a flax egg, and coconut and almonds for the mix ins.

  3. Can I use the mini size candy bars in this for my add-ins? (Leftover Halloween candy of Snickers, Milky Way, etc.) If so do I need to chop them? (They’re the tiny square size.) Thank you!