Prepare the boiling water for the hot water bath.
Preheat the oven to 180℃.
Chop up the chocolate and place into a heatproof bowl. Cut the butter into 2 cm chunks and add to the bowl.
Heat the chocolate and butter in the microwave for 1:30. It's okay if it doesn't completely melt at this point. Set in the water bath and mix while slowly melting the rest of the way.
When the chocolate and butter have completely melted, mix in the sugar (while still in the water bath).
Add one of the eggs and mix. Once mixed, add in the other egg and mix. It's okay if you add the eggs without beating first. Do this in the water bath as well.
Continue mixing until glossy, mixing slowly so as not to form bubbles (still in the water bath).
Transfer to the aluminum cup and drop onto a table to release any air bubbles. Bake at 180℃ for 20 minutes.
It's done! It'll be puffed up when baked, but will dent as it cools.
If you use a 6 cm silicone cup, bake at 180℃ for 13 minutes.
The center won't be hard, but it will firm up when cooled. When eating, bring it to room temperature or eat chilled. You can also warm it in the microwave for 30 seconds to melt the center.
Once cooled, you can cleanly remove it from the pan.
Note: In the summer, you don't even need to use the water bath to melt it! Super easy!
Note: If you add some rum, brandy, or cognac at the end, it will have an adult taste! Use 1~2 tablespoons!
Note: If you change the bar chocolate to confectionery chocolate and the butter to cultured butter, it will be even more rich! It's great for presents.
Story Behind this Recipe
I made an easy version of a recipe I saw in a book and it was unexpectedly delicious. It only takes 4 ingredients!
You can use your hands to break up the bar chocolate from within the foil, so you don't need a knife. If you follow all the steps in a hot water bath, it will turn out great. When mixing, be careful not to let it bubble and it will be rich. Bake until the inside is nice and soft and a little under-baked.