- 1 tbsp unsalted butter
- 1 tbsp heavy cream
- 1 large egg
- 2 tbsp unsweetened cocoa powder
- 2 tbsp granulated white sugar
- 1 tbsp creamy peanut butter
Add butter to a large microwave-safe mug. Melt in microwave. It is important to add the butter first because it will also help grease the bottom of the mug.
Add in heavy cream and whisk. Adding the heavy cream in next will help cool down the butter so it is not too hot when you add in the egg.
Add egg and whisk until batter is smooth. Make sure there are no egg white streaks at this stage. If you wait until you add the cocoa, you will no longer be able to see if there are any unmixed egg streaks.
Add cocoa powder and sugar. Whisk until batter is smooth.
Add 1 tbsp of peanut butter to the center of the batter. When dropping the peanut butter in, I recommend trying to spread the peanut butter out a little so that it is not dropped all on the same spot. So for example, add about 1/2 a tbsp to the very center of the batter. Then add 1/4 tbsp slightly to the right of that first dollop and add remaining 1/4 tbsp slightly to the left of that dollop. This ensures peanut butter throughout the middle and not just in one small spot. Do not push the peanut butter down into the batter. Doing so will cause the peanut butter to completely sink to the bottom. The peanut butter will sink in gradually as it cooks.
Cook the cake at full power in the microwave for about 45-60 seconds or until center fluffs up and looks set, but edges remain slightly gooey. Because the cake cooks very fast, I recommend cooking for 40 seconds and then checking on the cake. Continue to cook at 5 second intervals. I used a 1100 watt microwave. You may need to adjust your microwave power or time if your microwave is a different wattage.
Flip mug upside down to pour cake onto a plate. The remaining gooey batter should pour on top of the cake like a glaze. You can also skip plating and eat the cake directly from the mug.
- You can replace the sugar with a sugar substitute like erythritol. You will likely need to add more erythritol to equal 2 tbsp of sugar.
- I used a 1100 watt microwave. If your microwave has a different wattage, you will need to adjust cooking time or power.
- The cake cooks very fast. I recommend stopping at 40 seconds to check on it and then cooking at 5 second intervals, otherwise the cake could easily overcook. My cake took about 50 seconds total.
- Unlike a traditional lava cake, this cake will cook first in the center and the edges will be the last to finish cooking. You will want the center to fluff up and be set but the edges to still be gooey.
- It's okay for the edges of the cake to still be gooey. The remaining molten batter will pour over your cake, giving you some of that molten liquid chocolate. You don't want the cake to cook all the way because then the peanut butter in the center will overcook and no longer be creamy.
- I recommend using a creamy, natural peanut butter as it will be easier to spoon into the center of the batter.
- Some of the peanut butter will likely leak to the bottom of the cake when it cooks. This is normal. As long as you don't push down on the peanut butter before cooking the cake or don't add too much peanut butter, most of the peanut butter will stay in the cake. The part that leaks through will just be a molten peanut butter cover on top of the cake when you flip it onto a plate.
- I recommend using a large oversized mug where the bottom resembles the shape and size of an 8 oz ramekin so that your cake will look similar to a baked ramekin version.
- This cake can be cooked in the oven. Cook the cake in a greased 8 oz ramekin at 350F for about 10-15 minutes or until edges are set and middle is not set.
- Nutrition is calculated using sugar. If you use a sugar substitute, the carb count and calorie count will be less.