Dessert

Cosmic Brownie Protein Muffins (Sugar-Free Cake Mix + Fairlife)

Name: Cosmic Brownie Protein Muffins
Prep time: 8 min
Cook time: 20 min
Total time: 28 min
Yield: 12
Cuisine: American
Ingredients: 1 box sugar-free chocolate cake mix; 1 bottle chocolate Fairlife protein shake; ½ cup sugar-free chocolate chips; 1–1½ tsp coconut oil; ¼–⅓ cup Cosmic Brownie rainbow chips

These Cosmic Brownie Protein Muffins taste like the nostalgic Little Debbie treat but deliver a serious protein punch! Made with sugar-free chocolate cake mix and a chocolate Fairlife protein shake, they come together in one bowl, bake in under 25 minutes, and get finished with a shiny sugar-free chocolate glaze and those signature rainbow Cosmic chips on top!

High-protein, lower-sugar, and actually delicious- perfect for breakfast, post-workout, or a sweet snack that won’t completely wreck your macros.

How to Make Cosmic Brownie Protein Muffins

Yield: 12 muffins

Prep Time: 10 minutes

Cook Time: 18–22 minutes

Total Time: 30–35 minutes

Why You’ll Love These Healthy Cosmic Brownie Protein Muffins

Only a few main ingredients
Uses the viral cake-mix + protein shake base that actually works
Soft, chocolatey crumb with a Cosmic Brownie finish
Easy to meal-prep and freeze

Ingredients

Muffins

1 box (15–16 oz) sugar-free chocolate cake mix (Pillsbury Zero Sugar Devil’s Food or similar)
1 bottle (11.5–14 oz) chocolate Fairlife Core Power protein shake (or Fairlife chocolate milk protein shake)

Cosmic Topping

½ cup sugar-free chocolate chips (Lily’s, ChocZero, or similar)
1–1½ teaspoons coconut oil
¼–⅓ cup Cosmic Brownie rainbow chips (candy-coated chocolate chips / rainbow chip sprinkles)

Optional but recommended

Nonstick cooking spray or paper liners
Pinch of salt (if your cake mix is very sweet)

Instructions

Preheat & prep – Preheat oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly spray with nonstick spray.
Make the batter – In a large bowl, pour the entire bottle of chocolate Fairlife protein shake into the sugar-free chocolate cake mix. Stir with a whisk until completely smooth and no dry pockets remain. The batter will be thick but pourable — similar to a thick brownie batter. Do not overmix.
Fill the pan – Divide the batter evenly among the 12 muffin cups (about ¾ full). Smooth the tops slightly with the back of a spoon.
Bake – Bake for 18–22 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs (not wet batter). The tops should spring back lightly when touched. Start checking at 18 minutes — protein muffins can dry out if overbaked.
Cool – Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. The glaze sticks best to cooled muffins.
Make the Cosmic glaze – In a small microwave-safe bowl, combine the sugar-free chocolate chips and coconut oil. Microwave in 20-second intervals, stirring between each, until smooth and glossy (usually 40–60 seconds total). The coconut oil thins the chocolate so it brushes on easily and sets with a soft shine.
Finish the muffins – Working quickly, use a pastry brush, a new paint brush, or the back of a small spoon to “paint” a thin layer of the melted chocolate mixture over the top of each cooled muffin. Immediately sprinkle the Cosmic Brownie rainbow chips on top so they stick. Let the glaze set for 10–15 minutes before serving or storing.

Tips for the Best Results

Cake mix brands: Pillsbury Zero Sugar and similar sugar-free mixes work best. Regular cake mix will also work but will be higher in sugar.
Shake size: Most Fairlife Core Power bottles are 11.5–14 oz. If yours is on the smaller side and the batter seems too thick, add 1–2 tablespoons of water or unsweetened almond milk.
Don’t skip the coconut oil: It keeps the glaze soft and brushable instead of seizing into a hard shell.
Rainbow chips: Look for “Cosmic Brownie sprinkles,” “rainbow candy-coated chocolate chips,” or “rainbow chip sprinkles.” They’re available on Amazon, Walmart, and some craft/baking stores.
Extra protein boost (optional): Stir 1–2 scoops of chocolate protein powder into the dry cake mix before adding the shake. You may need an extra splash of liquid.
Texture note: These are denser and more brownie-like than traditional bakery muffins because of the protein shake. That’s normal and part of the appeal!

Storage & Make-Ahead

Room temperature: 1–2 days in an airtight container.
Refrigerator: Up to 5 days.
Freezer: Wrap individually and freeze up to 2 months. Thaw at room temperature or microwave 20–30 seconds.
The glaze stays soft in the fridge but firms slightly when cold.

Frequently Asked Questions

Can I make these without the Cosmic topping?

Yes — they’re still excellent plain or with a simple dusting of sugar-free chocolate chips mixed into the batter.

Can I use a different protein shake?

Yes. Any ready-to-drink chocolate protein shake of similar volume works. Fairlife gives the best texture and flavor in testing.

Why is the batter so thick?

Protein shakes have less liquid than the oil + eggs + water the cake mix was designed for. This is intentional and creates a denser, more satisfying muffin.

Can I make mini muffins?

Yes. Reduce bake time to 12–15 minutes and watch closely.