Do you ever crave a sweet treat in the afternoon with your tea or coffee? This keto blueberry mug cake recipe is your answer. It's a fluffy, single-serve cake that cooks in just one minute, perfect for those moments when you want a simple and quick dessert. This gluten-free, sugar-free mug cake is a variation on the vanilla keto mug cake, customized with a super fruity blueberry center.
What is a Mug Cake?
If you've never made a mug cake before, it's a single-serve cake made in a mug, cup, or ramekin. It requires minimal preparation and cooks in the microwave. The use of egg and baking powder allows the microwave cake to rise and become fluffy.
Why Blueberries?
Blueberries are a great fruit choice for a keto diet. They are low in net carbs, packed with antioxidants, and contain high amounts of vitamin C and fiber. A half cup of raw blueberries contains approximately 10.5 total grams of carbs.
Ingredients You'll Need
You only need a few simple ingredients to make this low-carb mug cake:
- Almond flour
- Coconut flour
- Sweetener (granulated erythritol monk fruit sweetener blend, allulose, Swerve, monkfruit, Erythritol or Xylitol)
- Baking powder
- Egg (medium if using regular almond flour, large if using super fine almond flour)
- Butter (melted and cooled)
- Vanilla extract
- Blueberries (fresh or frozen)
Step-by-Step Instructions
This section contains step-by-step instructions that show how to make this recipe.
Read also: Delicious Keto Coffee Cake
- Combine dry ingredients: In a small bowl, stir together the almond flour, coconut flour, baking powder, and sweetener. Be sure to break up any lumps.
- Whisk wet ingredients: In a second bowl, whisk the egg. Then, add the melted and cooled butter plus the vanilla extract and whisk until combined.
- Mix batter: Now, add the dry ingredients to the wet and stir until a smooth batter forms.
- Prepare mug: Grease a mug or ramekin with butter.
- Fill mug: Pour the batter into the mug. If you fill the cup or ramekin to the top with batter, it will overflow and create a mess. Therefore, choose a cup that holds a minimum of 200ml. You want to have at least 2 fingers of space at the top so the cake can rise.
- Add blueberries: I like to dust my blueberries in coconut flour before adding them to the batter. Coconut flour is very absorbent and it prevents the blueberries from sinking to the bottom of the mug. Press the blueberries into the center, leaving a little gap at the top to create a soft blueberry center. You can also stir them into the batter like you would for a blueberry muffin. If using frozen blueberries, rinse and pat the berries dry, then proceed as per recipe.
- Microwave: Microwave for 80 seconds at 900 watts. After this time, check whether the cake is done. The cake works best with heavy cream but if you don't have heavy cream, you can use coconut cream or whole milk.
Microwave Wattage Adjustments
My microwave operates at 900W and my cake took 80 seconds to cook. 600W = low power. Some microwaves are more or less powerful. You may need to adjust the cooking type based on the wattage of your microwave. If you have a more powerful microwave, you may need to cook the cake for 70 or 80 seconds instead of 90. In my opinion, it’s better to under cook then over cook, so if this is your first mug cake cook it for 80 seconds on full power. If it’s still wet in the middle, cook for 10 seconds longer.
Alternative Cooking Methods
Oven
Yes, you can! Preheat the oven to 180C / 350F electric or 160C / 320F fan assisted. Bake for 12-15 minutes or until a skewer or toothpick inserted comes out clean with no crumbs sticking.
Air Fryer
Yes. Set the temperature to 160C / 320F and check for doneness after 10 minutes.
Frosting (Optional)
If serving with frosting, mix the butter, cream and powdered allulose until smooth. If too thick to drizzle, add extra cream. Drizzle over the mug cake.
Tips and Tricks for the Perfect Keto Blueberry Mug Cake
- Coconut Flour: Unlike some other mug cake recipes, this one uses coconut flour. Coconut flour is highly absorbent, resulting in a thicker batter. Make sure to carefully measure out the coconut flour. If you wish to use coconut flour instead of almond, use just 1 tbsp.
- Sweetener: The reason I use allulose is because it’s a no calorie no carb sweetener like erythritol, but it doesn’t have the cooling effect. Remember that erythritol is 70% less sweet than allulose.
- Berries: Use other berries: Raspberries, blackberries or even cubed strawberries.
- Protein Powder: You can use any kind of protein powder here. Whey, egg white, plant-based, or even collagen. But if you do choose collagen (and its close cousin, bone broth protein), you may find the cake doesn’t rise as well. It may also be a little more gummy. You may need to cook it longer to offset this. If you choose not to use protein powder, you will need an additional 3 tablespoons of almond flour and another 1/4 teaspoon of baking powder. It will be higher in carbs.
- Mug Size: To make a mug cake, you’ll need a microwave-safe mug that’s at least 10 oz.
- Doneness: This cake rises quite high while it cooks and then will sink back down.
Variations and Substitutions
- Nut-Free: If you want to make the recipe nut-free, use 1 tablespoon of coconut flour instead of 2 tablespoons of almond flour.
- Coconut-Free: For a coconut-free version, use 2 tablespoons of almond flour instead of 1 tablespoon of coconut flour.
- Egg Substitute: Although I like this combination, some of you may perceive it as too "eggy". You can try the following: use one egg, double all the dry ingredients and add 1/4 cup coconut milk, almond milk or cream. This mixture will make 2 mug cakes.
- Sweetener: Instead of the listed sweeteners, you can try other healthy low-carb sweeteners from this list. The reason I'm using both Erythritol and stevia is to mask the aftertaste some of the sweeteners may have.
Serving and Storage
Mug cakes are best eaten straight away. It is possible to store it in an airtight container in the fridge for up to 2 days if necessary. You can also freeze it for up to 3 months. Once baked, cover them tightly and store at room temperature for up to 2 days. You can also store them in the refrigerator for up to 5 days. To reheat, place it in the microwave for 15-20 seconds until just warm.
Read also: Easy Low-Carb Cheese Crackers
Nutritional Information
5.9g net carbs per mug cake. Nutrition is calculated per cake. The information shown is an estimate provided by an online nutrition calculator. This lemon blueberry mug cake recipe has 7.6g of carbs and 2.3g of fiber per serving. If you count net carbs, that comes to 5.3g carbs per mug cake.
Read also: Keto Calorie Counting: A Detailed Guide