Chocolate Protein Mug Cake (No Protein Powder, Air Fryer)

This chocolate protein mug cake is a fudgy, single-serve chocolate cake with a gooey center and about 16 grams of protein, with no protein powder. The protein comes from Greek yogurt, peanut butter and oat flour, and it bakes in the air fryer, so you don’t need a microwave.

Most protein mug cakes lean on a scoop of powder, which is often what makes them dry, rubbery or chalky. This one tastes like a small chocolate cake, and you can make it with ingredients you probably already have.

Quick recipe overview

• Prep time: 5 minutes
• Cook time: 10–12 minutes
• Rest time: 2 minutes
• Total time: about 20 minutes (including preheat)
• Servings: 1 mug cake
• Calories: about 315 per mug cake
• Protein: about 17 g per mug cake
• Dietary: vegetarian, no eggs, no protein powder. Gluten-free if you use certified gluten-free oats.

Why you’ll love this recipe

• About 16 grams of protein with no powder, from real ingredients: Greek yogurt, peanut butter and oats.
• Single serve, so there’s no full pan of brownies sitting on the counter.
• No eggs. Greek yogurt gives the structure.
• Made in the air fryer, for when the microwave isn’t an option or you want a softer, more cake-like crumb.
• Fudgy, molten center from a few chocolate chips pressed into the middle.
• Eight pantry ingredients and one bowl.

Ingredients

• ¼ cup (60 g) plain Greek yogurt. This is the main protein source and the egg replacement. Use thick, plain, unsweetened Greek yogurt; 2% or whole milk gives the softest crumb. Thinner regular yogurt makes the batter runny and lowers the protein.
• 1 tbsp (16 g) peanut butter. Adds richness, moisture and some protein. Use a smooth, drippy natural peanut butter. Almond butter or sunflower seed butter work the same way.
• 2 tbsp (30 ml) milk. Loosens the batter. Any dairy or unsweetened plant milk works.
• 1 tbsp (12 g) monk fruit sweetener. Use a granulated monk fruit blend; most US versions are blended with erythritol and measure like sugar. Coconut sugar or maple syrup work, but they add sugar.
• ¼ cup (25 g) oat flour. Gives the cake its structure. Use store-bought oat flour, or blend rolled oats until fine. Use certified gluten-free oats if you need it gluten-free.
• 2 tbsp (10 g) unsweetened cocoa powder. Gives the chocolate flavor and the fudgy texture. Natural or Dutch-process both work.
• ¼ tsp baking powder. Gives a little lift. Don’t add more, or the cake rises and then sinks.
• 1 tbsp (8 g) dark chocolate chips. Make the molten center. Use sugar-free chips if you want the cake to have no added sugar.

Equipment

• Air fryer
• Oven-safe ramekin or ceramic mug, 10–12 oz (check that it’s labeled oven-safe)
• Small bowl and whisk or fork
• Small piece of foil (optional)

How to make a chocolate protein mug cake

1. Preheat the air fryer to 320°F (160°C) for about 3 minutes. Grease your ramekin or mug. A lower temperature lets the center cook before the top over-browns.
2. Whisk the wet ingredients. Whisk the Greek yogurt, peanut butter, milk and monk fruit until completely smooth and glossy, with no streaks of peanut butter. Lumps of yogurt turn into dry pockets after baking.
3. Add the dry ingredients. Add the oat flour, cocoa powder and baking powder. Fold just until no dry flour is visible. The batter should be thick but spoonable, like brownie batter.
4. Fill the mug. Spoon the batter into the mug and smooth the top. It should fill the mug no more than about halfway so it has room to rise.
5. Add the chocolate center. Press the chocolate chips into the middle of the batter until they’re just covered.
6. Air fry for 10–12 minutes. Check at 6 minutes; if the top is browning fast, lay a small piece of foil loosely on top. Start checking for doneness at 10 minutes. It’s done when the edges pull away slightly, the top is set and springs back lightly, and the very center still looks a little glossy. A toothpick near the edge should come out with moist crumbs.
7. Rest for 2 minutes. The cake keeps cooking from the heat of the mug, and the center firms up just enough. Eat it warm.

Tips for the best protein mug cake

• Take it out early. A slightly glossy center turns fudgy as it rests. Cooked until fully firm, it turns dry.
• Use thick yogurt. Strained Greek yogurt gives the best structure and the most protein.
• Stir peanut butter well first. If the oil has separated, mix it back in before measuring.
• Don’t overmix after adding the flour. Stop as soon as the flour disappears.
• Know your air fryer. Basket and oven-style air fryers heat differently. Write down your time once you’ve made it.

Common mistakes

• Dry, rubbery cake. It was overbaked. Take it out while the center still looks shiny, and check at the earliest time.
• Raw, wet middle. The temperature was too high (the top set before the inside cooked), or the mug is very deep. Bake at 320°F and use a wider ramekin.
• Burnt top. The cake is too close to the heating element. Cover loosely with foil at 6 minutes.
• Cake overflowed. The mug was too small. Use a 10–12 oz mug and fill it no more than halfway.
• Bitter taste. Too much cocoa, or not enough sweetener for your taste. Taste the batter and adjust the sweetener before baking.

Substitutions

Original	Substitute	Effect	Recommended?
Greek yogurt	Plain skyr (same amount)	Similar texture and protein	Yes
Greek yogurt	Dairy-free Greek-style yogurt	Lower protein; texture may be softer (not tested)	Use with caution
Peanut butter	Almond butter or sunflower seed butter	Same texture, different flavor	Yes
Monk fruit	Coconut sugar or maple syrup (1 tbsp)	Adds sugar; maple syrup makes the batter slightly thinner	Yes
Oat flour	All-purpose flour	No longer gluten-free; slightly lighter crumb (not tested)	Use with caution
Dark chocolate chips	Sugar-free chocolate chips	Removes the added sugar	Yes

Variations

• Peanut butter swirl: drop a small spoonful of peanut butter into the center instead of the chips.
• Mocha: whisk ¼ tsp instant coffee into the milk.
• Berry: press a few raspberries into the center instead of the chips.
• Dairy-free: use plant yogurt and plant milk (lower protein; recalculate).

Storage

This is best eaten warm, within a few minutes of baking; the molten center doesn’t stay molten once it cools. Refrigerator and freezer storage haven’t been tested for this recipe.

Make-ahead tip

You can measure the dry ingredients (oat flour, cocoa, baking powder) into a small jar ahead of time. When you want one, whisk the wet ingredients and stir in the jar.

Serving suggestions

• A spoonful of Greek yogurt on top for more protein
• Fresh raspberries or sliced strawberries
• A dusting of cocoa powder

Nutrition information (per mug cake, estimated)

Nutrient	Amount
Calories	~315 kcal
Protein	~17 g
Carbohydrates	~34 g (excludes erythritol from the monk fruit blend)
Total fat	~16 g
Saturated fat	~5 g
Fiber	~6 g
Sugar	~9 g
Added sugar	~4 g (from regular dark chocolate chips; ~0 g with sugar-free chips)
Sodium	~220 mg

Nutrition information is an estimate and may vary depending on the brands and ingredients used. Assumptions: 2% plain Greek yogurt with 10 g protein per 100 g, natural lightly salted peanut butter, 2% milk, granulated monk fruit–erythritol blend, semisweet dark chocolate chips.

Nutrition notes

• Protein: most of it comes from Greek yogurt (~6 g), peanut butter (~4 g), oat flour (~3.5 g) and cocoa (~2 g).
• Fiber: about 6 g, mostly from cocoa powder and oats.
• Added sugar: only from the chocolate chips. With sugar-free chips, the recipe has no added sugar.

FAQs

Can I make this protein mug cake in the microwave? This recipe was written for the air fryer. Microwave timing hasn’t been tested for this version, but microwave mug cakes typically cook in short bursts of about a minute, and they’re easy to overcook.

How much protein is in this mug cake? About 16–17 grams per mug cake, depending on your Greek yogurt. Check your yogurt’s label: thinner yogurts have less protein.

Can I make it without peanut butter? Yes. Almond butter or sunflower seed butter work the same way.

Is this mug cake gluten-free? It is when you use certified gluten-free oat flour. Regular oats can be cross-contaminated with wheat.

Does it have eggs? No. Greek yogurt replaces the egg.

Why is my mug cake dry? It baked too long. Take it out while the center still looks slightly shiny, and let it rest.

Why is my mug cake raw in the middle? The air fryer may be too hot, or the mug too deep. Bake at 320°F and use a wider, shallower ramekin.

Can I use a regular coffee mug? Only if it’s labeled oven-safe. Many decorative mugs aren’t made for oven or air fryer heat.

Can I make it less sweet? Use half the monk fruit, or use extra-dark chocolate chips.

Can I double it? Yes. Bake it in two separate mugs, not one larger mug, so the timing stays the same.

Final thoughts

If you want a warm chocolate dessert with real protein and no protein powder, this mug cake is a good one to keep in your back pocket. Have one more look at the center when you pull it out: a little shine is what you want. Watch the video above to see exactly what done looks like, and tell me in the comments how long your air fryer took.