How to Make Peanut Butter Chocolate Protein Bars

Ingredients

Quick oats: Absorb moisture more evenly than rolled oats, creating a softer, chewier bar. Avoid using steel-cut oats, as they won’t soften properly.

Whey chocolate protein powder: Look for a brand that blends smoothly without a chalky texture. Some protein powders absorb more liquid than others, so if using a different brand, you may need to adjust the Fairlife milk slightly.

Collagen peptides: Unflavored collagen works best to avoid altering the taste. Can be omitted without affecting texture.

Chia seeds: Whole chia seeds add texture and binding power. If you prefer a smoother bar, ground chia seeds can be used instead.

Cinnamon: Adds warmth and enhances the chocolate and peanut butter flavors without overpowering them.

Dark chocolate, chopped: Use high-quality dark chocolate for the best flavor and meltability. Chocolate chips work in a pinch but won’t melt as smoothly.

Creamy peanut butter: Use a no-stir peanut butter like Jif or Skippy for consistent texture and binding. Natural peanut butter hasn’t been tested and may make the batter too wet due to its thinner consistency and oil separation.

Honey: Provides sweetness and chewiness. Raw honey works, but regular honey blends more smoothly. Maple syrup can be substituted but may slightly change the texture.

Melted butter or coconut oil: Use unsalted butter for better control of salt levels. If using coconut oil, refined coconut oil has a neutral flavor, while unrefined adds a subtle coconut taste.

Fairlife milk: This ultra-filtered milk adds extra protein and creaminess. If substituting with regular milk, note that it contains less protein, which may slightly affect texture.

Vanilla extract: Pure vanilla extract provides the best flavor, but imitation vanilla works if needed.

Egg: Use a large egg at room temperature egg.

See Recipe Card for quantities.

Instructions

1. Preheat the oven and line an 8x8-inch baking dish with parchment paper, lightly greasing it to prevent sticking.

2. In a large mixing bowl, whisk together quick oats, whey chocolate protein powder, collagen peptides, chia seeds, cinnamon, and salt until evenly combined.

3. Melt chocolate, stirring until smooth. Stir in peanut butter, honey, and melted butter until fully combined. Whisk in Fairlife milk, vanilla extract, and egg until the mixture is smooth and slightly thickened.

4. Pour the wet mixture into the dry ingredients and stir until fully incorporated. The batter should be sticky but scoopable. If too thick, add a little more milk.

5. Transfer the mixture to the prepared baking dish and press it firmly into an even layer.

6. Bake until the edges are set but the center is slightly soft. Let cool completely in the pan before slicing into bars.

Substitutions

Quick oats: Substitute rolled oats, but pulse them briefly in a food processor for a softer texture. Do not use steel-cut oats, as they won’t soften properly.

Whey chocolate protein powder: Vanilla whey protein will provide a neutral flavor and still complement the chocolate and peanut butter. Chocolate peanut butter whey protein would also work well.

Collagen peptides: Omit if needed.

Chia seeds: Substitute ground flaxseeds (flax meal) in a 1:1 ratio. Whole flaxseeds will not absorb liquid properly.

Dark chocolate, chopped: Substitute semi-sweet chocolate for a slightly sweeter taste, or use chocolate chips, though they may not melt as smoothly.

Honey: Substitute maple syrup in a 1:1 ratio. The bars may be slightly softer. Do not use granulated sugar, as it will not provide the same binding properties.

Melted butter or coconut oil: Use an equal amount of vegetable oil or ghee. The flavor may vary slightly, but the texture will remain the same.

Fairlife milk: Substitute with regular whole milk in a 1:1 ratio. This will slightly reduce the protein content but will not affect the texture.

Variations

Gluten-Free: Already is!

Nut-Free: Use sunflower seed butter instead of peanut butter, and check that your protein powder is nut-free.

Dairy-Free: Use coconut oil instead of butter and swap Fairlife milk for an unsweetened dairy-free milk alternative like oat or almond milk. 

Feed a Crowd: Double the recipe and bake in a 9x13-inch pan. Bake time may need to be increased slightly.

Equipment

8x8-Inch Professional Square Baking Pan: The ideal size for bars with the right thickness. A 9x9-inch pan can be used, but bars will be slightly thinner. I like this one because it has 90 degree corners. (Affiliate Link)

Storage

Refrigerate: Store bars in an airtight container at room temperature for up to 3 days or in the refrigerator for up to 1 week.

Freeze: These bars freeze well. Wrap individually in plastic wrap, then place in a freezer-safe container for up to 1 month. Thaw at room temperature for 10-15 minutes before eating.

Reheat: No reheating needed—these bars are best enjoyed at room temperature or slightly chilled straight from the fridge.