May 10, 2018


Where are all my peanut butter lovers at? This recipe is for you! After making some bomb Collagen Protein Brownies, sinful Sugar Cookie Collagen Protein Bars, and crave-worthy Cookie Dough Collagen Bars, I just HAD TO make these Peanut Butter Collagen Protein Blondies. These bars have a gooey, chewy blondie texture with rich peanut butter, peanut butter chips, and actual roasted peanuts. It’s a peanut goodness overload! But don’t worry, each 2″x2″ square is just over 100 calories, with 2 grams of sugar and 10 grams of protein – not to mention, they’re gluten-free and dairy-free!

Did you know? Double-blind, placebo-controlled studies indicate that collagen supplementation can significantly improve skin elasticity and moisture, even reduce wrinkles!


Collagen substitutions

I used Vital Proteins Unflavored Collagen Peptides to add protein and health benefits! The right amount of collagen doesn’t ruin the taste or texture of baked goods. If you don’t have collagen peptides, you can substitute an additional half cup (60g) of gluten free 1-to-1 baking flour, or 60 grams of another protein powder (such as whey, whey-casein blend, or plant-based protein). If using whey or casein, you may also want to replace a quarter cup of the egg whites with unsweetened applesauce, buttery spread, oil, or cashew butter so they stay moist. You just can’t use as much of these other protein powders (without other modifications) or the bars will come out dry and dense. That’s the “beauty” of collagen!


Flour substitutions

I used gluten free baking flour to mimic the texture of traditional blondies. However, you could sub half as much (one-quarter cup) coconut flour to reduce the carb content. If you don’t have gluten free baking flour, feel free to use all-purpose flour, brown rice flour, cake flour, cassava flour, sweet white sorghum flour, fine oat flour, or tapioca flour. For almond flour, increase the measurement to one full cup.


Sweetener substitutions

To add sweetness without any sugar, I used Pyure Organic Stevia Blend, a calorie-free blend of stevia and erythritol that’s twice as sweet as sugar. A virtually identical substitute would be Truvia Natural Sweetener. You can substitute baking stevia, granulated erythritol, or granulated sugar like coconut sugar; but you will need about twice as much (one cup) to achieve the same level of sweetness. If using stevia extract or drops, please refer to the brand-specific conversion chart.

I used Truvia Brown Sugar Blend to add the richness of brown sugar with half the sugar, but you can substitute an equal measure of Pyure Organic Stevia Blend, or twice as much baking stevia, granulated erythritol, or granulated sugar like coconut sugar.


Other substitutions

Nut butter works great in these bars because collagen baked goods need a little extra help holding together! Nut butters are better for binding than butter or oil. Of course I went for peanut butter because after all, these are peanut butter blondies! That said, any nut butter will do, if you don’t mind altering the taste. The egg whites may be substituted for an equivalent amount of egg replacer or three chia eggs (3 tbsp. white chia seeds soaked in 1/2 cup warm water). The butter extract, peanut butter chips and dry-roasted peanuts are optional, but highly recommended.

Now, here’s the recipe for these Peanut Butter Collagen Protein Blondies! I’d love for you to rate and/or comment below if you try it 😉

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Peanut Butter Collagen Protein Blondies

These Peanut Butter Collagen Protein Blondies are gooey, rich, and full of peanut butter flavor. Gluten-free, high protein, and low carb!
Course Dessert
Prep Time 15 minutes
Cook Time 20 minutes
Servings 16 servings
Calories 92kcal


  • 1 cup (120g) unflavored collagen peptides*
  • 1/2 cup (65g) gluten-free baking flour*
  • 6 tbsp. calorie-free sweetener*
  • 2 tbsp. brown sugar alternative*
  • 1/2 tsp. baking soda
  • 1/2 tsp. salt optional
  • 1/2 cup creamy peanut butter*
  • 1/2 cup (4 large) egg white
  • 1/4 cup unsweetened almond milk*
  • 1 1/2 tsp. vanilla extract
  • 1/2 tsp. butter extract optional
  • 1 oz. dry-roasted peanuts optional
  • 1 oz. peanut butter chips optional

*See blog post above for substitutions.


    • Preheat oven to 350 degrees F.
    • Whisk together dry ingredients in a medium bowl (through salt).
    • Add wet ingredients (through extracts) and mix until smooth and thick.
    • Stir in dry-roasted peanuts and peanut butter chips if desired.
    • Line an 8″x8″ baking pan with parchment paper, or lightly coat with cooking spray and spread batter over the bottom of pan.
    • Bake for 20-25 minutes, or until a toothpick or knife inserted comes out slightly dirty.
    • Let pan cool for 10 minutes, then cut into sixteen equal squares using a knife (use a plastic knife for a cleaner cut).
    • Will keep in an airtight container in the fridge for one week, or in the freezer for one month.


    Calories (per serving, minus optionals): 92kcal, Fat: 3.6g, Sat fat: 0.8g, Carbs: 5g, Fiber: 1g, Sugar: 1g, Protein: 9g, Sodium: 132mg
    Calories (per serving, including optionals): 116kcal, Fat: 5.0g, Sat fat: 1.3g, Carbs: 8g, Fiber: 1g, Sugar: 2g, Protein: 10g, Sodium: 208mg

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