5-Minute Chocolate Jar Cake
This chocolate jar cake gets you from craving to spoon in about five minutes flat. It bakes right in a small glass jar, so there is no mixing bowl to wash and no leftover slices to stash away.
The cake tastes like a real chocolate layer cake, with a tender crumb and deep cocoa flavor. A minute and a half in the microwave turns pantry ingredients into a warm, steaming dessert you eat straight from the jar.
Why This Little Cake Works
I love that it is a true single-serving treat. The recipe uses no egg, which keeps the texture soft instead of rubbery, and the jar traps steam so the crumb stays moist.
It also scratches that chocolate itch without leaving me with an entire cake on the counter. The whole thing comes together before the kettle boils.
Ingredients
- 3 tbsp all-purpose flour: spoon it into the tablespoon and level it, do not scoop from the bag
- 2 tbsp granulated sugar
- 2 tbsp unsweetened cocoa powder: Dutch-process gives a darker, rounder chocolate taste; natural cocoa works too
- 1/4 tsp baking powder: this gives the cake its lift, so check the expiry date
- Pinch of salt
- 3 tbsp whole milk: any milk works, including oat or almond
- 1 tbsp vegetable oil: neutral oil like canola or avocado; melted butter is fine but the cake will be a little denser
- 1/4 tsp vanilla extract
- 1 tbsp chocolate chips: optional, but they melt into little pockets of gooey chocolate
Variations / Substitutions
- Dairy-free: swap the milk for oat milk; the cake will still be moist and tender
- Mocha jar cake: dissolve 1/2 tsp instant coffee in the milk before adding it to the dry ingredients
- Peanut butter swirl: drop a teaspoon of smooth peanut butter on top of the batter before microwaving and stir it in just once
- Gluten-free: use a 1:1 gluten-free flour blend instead of all-purpose
If you like this, the vanilla mug cake on the site is its lighter, buttery cousin.
How to Make 5-Minute Chocolate Jar Cake
Step 1: Mix the Dry Ingredients
Grab a half-pint (8 oz) glass jar and add the 3 tbsp flour, 2 tbsp sugar, 2 tbsp cocoa powder, 1/4 tsp baking powder, and the pinch of salt. Use a fork to whisk them together until the mixture looks even and dark, about 30 seconds.
You will see little clumps of cocoa breaking apart. Tapping the jar on the counter a couple times helps settle the powder so it does not fly up when you stir.
Step 2: Stir in the Wet Ingredients
Pour the 3 tbsp milk, 1 tbsp oil, and 1/4 tsp vanilla right into the jar. Stir with the fork until the batter is smooth and glossy, checking the bottom of the jar for any dry pockets. If you are adding chocolate chips, fold them in now.
The batter will look a little thin, and that is exactly right. Overmixing at this stage can make the cake tough, so stop as soon as no streaks of flour remain.
Step 3: Microwave and Serve
Place the jar in the microwave and cook on high for 60 to 90 seconds, until the cake has puffed up and the center looks just set but still slightly damp. Let it sit for 30 seconds – the cake finishes cooking from the carryover heat.
Top with a small scoop of vanilla ice cream or a dollop of whipped cream and eat it straight from the jar while it is still warm. The steam will melt the ice cream into the cake.
Tips for the Best Jar Cake
- Microwave wattage matters: Start with 60 seconds at 100 watts or higher; for lower wattages (700 to 800 W), go for 75 seconds first, then add 10-second bursts as needed.
- Use a wide-mouth jar: A regular-mouth jar makes it trickier to stir evenly and harder to eat out of with a spoon.
- Warm the jar briefly: Rinse the jar under hot water, then dry it before adding the dry ingredients. The batter bakes more evenly when the glass is not ice-cold.
If you want to make two jars at once, here is how the ingredients scale:
| Ingredient | 1 jar | 2 jars |
|---|---|---|
| All-purpose flour | 3 tbsp | 6 tbsp |
| Sugar | 2 tbsp | 4 tbsp |
| Cocoa powder | 2 tbsp | 4 tbsp |
| Baking powder | 1/4 tsp | 1/2 tsp |
| Salt | pinch | 1/8 tsp |
| Milk | 3 tbsp | 6 tbsp |
| Oil | 1 tbsp | 2 tbsp |
| Vanilla | 1/4 tsp | 1/2 tsp |
Frequently Asked Questions
Can I bake this in the oven instead?
No, this recipe was developed for the microwave. An oven jar cake would need different ratios and a longer bake time.
Why did my cake overflow the jar?
It was likely cooked a few seconds too long, or the baking powder measurement was heaped. Stick to level tablespoons and start checking at 60 seconds.
Can I use a different sweetener?
Yes, you can swap the sugar for 2 tablespoons of maple syrup, honey, or agave. The texture will be slightly denser and the cake may need 10 fewer seconds in the microwave because the liquid sweetener speeds up cooking.
Chocolate Jar Cake Recipe
Ingredients
Method
- Add the flour, sugar, cocoa powder, baking powder, and salt to an 8 oz glass jar. Whisk with a fork until evenly combined.
- Pour in the milk, oil, and vanilla. Stir until the batter is smooth and no dry flour remains at the bottom. Fold in the chocolate chips if using.
- Microwave on high for 60 to 90 seconds, until the cake has puffed and the center appears just set. Rest 30 seconds, then top with ice cream and serve warm from the jar.
Notes
