Cinnamon Swirl Oatmeal Blondies

Featured in: Fall Baking

Enjoy chewy, golden blondies filled with a swirl of warm cinnamon and wholesome oats. These comforting bars start with a buttery batter layered and swirled with cinnamon-sugar, creating a marbled effect. Perfect for simple weeknight baking, each square offers cozy spice and rich sweetness. Pair with ice cream or drizzle with a glaze for extra indulgence. Great for gatherings, these American-style treats use easy pantry ingredients, come together in under forty minutes, and require just basic kitchen tools. Vegetarian-friendly and satisfying in texture and warmth.

Updated on Wed, 29 Oct 2025 14:05:00 GMT
Chewy cinnamon swirl oatmeal blondies warm from the oven, a perfect comfort dessert.  Save to Pinterest
Chewy cinnamon swirl oatmeal blondies warm from the oven, a perfect comfort dessert. | yummywithmia.com

Chewy, golden blondies infused with a warming cinnamon swirl and wholesome oats—a comforting treat perfect for any occasion.

The first time I made these blondies, my kitchen filled with the comforting aroma of cinnamon and butter. Sharing warm slices with friends on a rainy afternoon made them an instant favorite in our home.

Ingredients

  • Unsalted butter: 1 cup (225 g), melted and slightly cooled
  • Light brown sugar: 1 cup (200 g), packed
  • Granulated sugar: ½ cup (100 g)
  • Eggs: 2 large
  • Vanilla extract: 2 tsp
  • All-purpose flour: 1 ½ cups (190 g)
  • Old-fashioned rolled oats: 1 cup (90 g)
  • Baking powder: ½ tsp
  • Baking soda: ½ tsp
  • Salt: ½ tsp
  • Light brown sugar (swirl): ⅓ cup (67 g), packed
  • Ground cinnamon (swirl): 1 ½ tsp
  • Unsalted butter (swirl): 2 tbsp (30 g), melted

Instructions

Prep the Pan:
Preheat oven to 350°F (175°C). Line a 9x9-inch (23x23 cm) baking pan with parchment paper, leaving an overhang for easy removal.
Mix Wet Ingredients:
In a large bowl, whisk together melted butter, brown sugar, and granulated sugar until well combined.
Add Wet Additions:
Add eggs and vanilla extract. Whisk until smooth.
Combine Dry Ingredients:
Stir in flour, oats, baking powder, baking soda, and salt just until combined. Do not overmix.
Prepare Cinnamon Swirl:
In a small bowl, mix all cinnamon swirl ingredients together until a thick paste forms.
Layer and Swirl:
Spread half the blondie batter into the prepared pan. Drop half the cinnamon swirl mixture in dollops over the batter and gently swirl with a knife or skewer.
Finish Layers:
Spread the remaining blondie batter on top, then dollop and swirl the rest of the cinnamon mixture.
Bake:
Bake for 25–28 minutes, or until the edges are golden and a toothpick inserted in the center comes out with a few moist crumbs.
Cool and Serve:
Cool completely in the pan before lifting out and slicing into squares.
Golden blondies with a rich cinnamon swirl served on a rustic plate for sharing.  Save to Pinterest
Golden blondies with a rich cinnamon swirl served on a rustic plate for sharing. | yummywithmia.com

These blondies have become a staple at our family get-togethers. Kids love swirling the cinnamon, and adults sneak extra squares when no one's looking.

Required Tools

Mixing bowls, 9x9-inch baking pan, whisk, rubber spatula, parchment paper, knife or skewer for swirling.

Allergen Information

Contains wheat (gluten), eggs, dairy (butter). Check oat labels for gluten-free needs.

Nutritional Information

Each serving contains: 235 calories, 11 g total fat, 32 g carbohydrates, 3 g protein.

Freshly baked cinnamon swirl oatmeal blondies, drizzled with icing, invite you to indulge. Save to Pinterest
Freshly baked cinnamon swirl oatmeal blondies, drizzled with icing, invite you to indulge. | yummywithmia.com

Slice after completely cooling for neat squares. Enjoy the comforting flavors any time you crave a sweet homemade treat.

Common Recipe Questions

How do I achieve a distinct cinnamon swirl?

Layer half the blondie batter, dollop cinnamon mixture, swirl gently, repeat with remaining batter and swirl mixture for vivid streaks.

Can I use quick oats instead of old-fashioned oats?

Old-fashioned oats provide chewy texture, but quick oats can be substituted for softer bars if preferred.

Is it possible to make these dairy-free?

Replace butter with a dairy-free margarine or vegan alternative. Check labels for other ingredients as needed.

How should I store the blondies for freshness?

Keep cooled squares in an airtight container at room temperature for up to three days or refrigerate for longer shelf life.

Can nuts be added for crunch?

Mix ½ cup chopped pecans or walnuts into the batter before baking for extra texture.

What's the best pan size to use?

A 9x9-inch square baking pan yields the suggested thickness and portion—use parchment paper for easy lift-out.

Cinnamon Swirl Oatmeal Blondies

Golden blondies packed with oats and cinnamon swirl—sweet, chewy, and perfect for sharing any time.

Prep Time
15 minutes
Cooking Duration
25 minutes
Overall Time
40 minutes
Created by Mia

Recipe Type Fall Baking

Skill Level Easy

Culinary Origin American

Total Output 16 Portion Size

Dietary Preferences Vegetarian-Friendly

What You'll Need

Blondie Batter

01 1 cup unsalted butter, melted and slightly cooled
02 1 cup light brown sugar, packed
03 1/2 cup granulated sugar
04 2 large eggs
05 2 teaspoons vanilla extract
06 1 1/2 cups all-purpose flour
07 1 cup old-fashioned rolled oats
08 1/2 teaspoon baking powder
09 1/2 teaspoon baking soda
10 1/2 teaspoon salt

Cinnamon Swirl

01 1/3 cup light brown sugar, packed
02 1 1/2 teaspoons ground cinnamon
03 2 tablespoons unsalted butter, melted

Steps to Follow

Step 01

Prepare Baking Pan: Preheat oven to 350°F. Line a 9x9-inch baking pan with parchment paper, leaving some overhang for easy removal.

Step 02

Combine Wet Ingredients: In a large mixing bowl, whisk together melted butter, light brown sugar and granulated sugar until fully incorporated.

Step 03

Add Eggs and Vanilla: Blend in eggs and vanilla extract, whisking until smooth and homogenized.

Step 04

Incorporate Dry Ingredients: Fold in all-purpose flour, rolled oats, baking powder, baking soda and salt, gently mixing until just combined. Avoid overmixing.

Step 05

Prepare Cinnamon Swirl: In a separate small bowl, mix together light brown sugar, ground cinnamon and melted butter to create a thick paste.

Step 06

Layer Blondie Batter and Swirl: Spread half of the blondie batter evenly into prepared pan.

Step 07

Create First Swirl: Drop half of the cinnamon paste in small dollops over the batter and gently swirl with a knife or skewer for a marbled effect.

Step 08

Add Second Layer: Spread remaining blondie batter evenly over swirled base.

Step 09

Top and Swirl Again: Dollop and swirl the rest of the cinnamon mixture across the surface.

Step 10

Bake: Transfer pan to oven and bake for 25–28 minutes, until edges are golden and a toothpick inserted in the center comes out with a few moist crumbs.

Step 11

Cool and Slice: Allow to cool completely in the pan before lifting out with parchment overhang and slicing into squares.

Tools Required

  • Mixing bowls
  • 9x9-inch baking pan
  • Whisk
  • Rubber spatula
  • Parchment paper
  • Knife or skewer

Allergy Warnings

Please review individual ingredients for potential allergens and reach out to a healthcare professional if unsure.
  • Contains wheat (gluten), eggs, and dairy (butter).
  • Check oat product labeling for gluten-free assurance if necessary.

Nutritional Info (per serving)

These details are for reference only and shouldn't replace professional medical consultation.
  • Calories Count: 235
  • Fats: 11 grams
  • Carbohydrates: 32 grams
  • Proteins: 3 grams