Ingredients
Equipment
Method
- Add the 4 tablespoons (30g) flour, 2 tablespoons (25g) sugar, and 2 tablespoons (11g) cocoa powder to a 12-ounce (350ml) or larger microwave-safe mug and stir with a spoon for 20 seconds, scraping the bottom and sides, until the color is completely even with no dry pockets or flour streaks remaining.
- Pour in the 3 tablespoons (45ml) whole milk and 2 teaspoons (9g) neutral oil and stir slowly from the bottom upward until the batter is thick, dark, glossy, and completely smooth with no dry streaks — if the batter feels too stiff, add a half teaspoon of milk and stir again.
- Use your fingertips to press the 1½ tablespoons (21g) chocolate chips into the center of the batter, pushing them just below the surface in a cluster rather than spreading them toward the edges or stirring them in.
- Place the mug in the center of the microwave turntable and cook on full power for 60 seconds in a 1000-watt microwave, checking that the top looks set and slightly domed while the center still appears soft — add 10 seconds if your microwave runs below 1000 watts, check at 50 seconds if it runs higher.
- Leave the mug on the counter untouched for 30 seconds to let carryover heat finish the center gently without overcooking the edges.
- Dust the top with powdered sugar using a small sieve and place a few whole chocolate chips on top immediately, then serve straight from the mug while still warm.
Notes
- Cocoa powder: Both natural and Dutch-process work
here. Dutch-process gives a darker, smoother, more
rounded chocolate flavor. Natural cocoa is slightly
sharper and more acidic. Measure level — never heaped. - Chocolate chips: Use 45–55% cacao semi-sweet chips
for the best melt. Cheap stabilized chips soften but
won't give a clean molten center. Guittard or
Ghirardelli recommended. - Milk substitution: Swap whole milk 1:1 with
unsweetened oat milk or almond milk for dairy-free.
Oat milk gives the closest result to whole milk. - Gluten free: Replace all-purpose flour 1:1 with a
gluten free 1-to-1 baking blend containing xanthan
gum. Do not use almond flour or coconut flour. - Storage: Make and eat fresh. The crumb dries out
within 30 minutes and the molten center sets
completely as it cools. Do not cover with plastic
wrap — trapped steam makes the top gummy. - Freeze unbaked: Pre-measure dry ingredients into a
small jar or zip-lock bag and store in the pantry
for up to 3 months. Add wet ingredients and
microwave when ready. - Make ahead: Not recommended for the baked cake.
The dry mix jar is the only make-ahead step
worth doing. - Altitude: Above 3,500 feet (1,065m), reduce
microwave time by 5 seconds and add an extra
half teaspoon (2.5ml) of milk to compensate
for faster moisture loss. - Scaling: This recipe is designed for one serving
in one mug. Do not double the batter in a single
mug — microwave two separate mugs one after the
other for two servings. - Allergens: Contains gluten (flour), dairy (milk,
chocolate chips). May contain traces of nuts
depending on chocolate chip brand. Check packaging
for allergen declarations. - Pro tip: Press chips into the center rather than
stirring them in — this is the technique that
creates the flowing molten chocolate pocket when
the cake is broken open.
here. Dutch-process gives a darker, smoother, more
rounded chocolate flavor. Natural cocoa is slightly
sharper and more acidic. Measure level — never heaped. - Chocolate chips: Use 45–55% cacao semi-sweet chips
for the best melt. Cheap stabilized chips soften but
won't give a clean molten center. Guittard or
Ghirardelli recommended. - Milk substitution: Swap whole milk 1:1 with
unsweetened oat milk or almond milk for dairy-free.
Oat milk gives the closest result to whole milk. - Gluten free: Replace all-purpose flour 1:1 with a
gluten free 1-to-1 baking blend containing xanthan
gum. Do not use almond flour or coconut flour. - Storage: Make and eat fresh. The crumb dries out
within 30 minutes and the molten center sets
completely as it cools. Do not cover with plastic
wrap — trapped steam makes the top gummy. - Freeze unbaked: Pre-measure dry ingredients into a
small jar or zip-lock bag and store in the pantry
for up to 3 months. Add wet ingredients and
microwave when ready. - Make ahead: Not recommended for the baked cake.
The dry mix jar is the only make-ahead step
worth doing. - Altitude: Above 3,500 feet (1,065m), reduce
microwave time by 5 seconds and add an extra
half teaspoon (2.5ml) of milk to compensate
for faster moisture loss. - Scaling: This recipe is designed for one serving
in one mug. Do not double the batter in a single
mug — microwave two separate mugs one after the
other for two servings. - Allergens: Contains gluten (flour), dairy (milk,
chocolate chips). May contain traces of nuts
depending on chocolate chip brand. Check packaging
for allergen declarations. - Pro tip: Press chips into the center rather than
stirring them in — this is the technique that
creates the flowing molten chocolate pocket when
the cake is broken open.