Instructions

1. Preheat the oven to 450 degrees Fahrenheit, assuming you will be baking these lava cakes right away (see notes for make-ahead option).
2. Prepare your muffin tin by heavily buttering only two of the cups (one on the center outside edge, the other on the opposite). See photos for reference and be sure to coat them well. Then sprinkle some cocoa powder into the buttered cups. Turn and tap the tin over the sink to lightly coat the insides of the cups with the powder. Set the tin aside.
3. Place the butter in a medium heat-safe mixing bowl and melt it in the microwave (alternately, gently melt it over low heat on the stove and then remove it from the heat). Add the chocolate to the bowl and stir until melted (if the chocolate won’t melt on its own, gently warm the mixture in the microwave in 30-second intervals, stirring after each, or over very low heat on the stovetop). Set aside.
4. Crack one egg and pour the egg white into a bowl for later use* or discard it. Pour the yolk into another medium-to-large mixing bowl. Crack the second egg into the yolk bowl (both the white and the yolk). Add the sugar, vanilla and salt. Beat the mixture with a whisk until foamy and pale, about 1 to 2 minutes.
5. Pour the egg mixture into the chocolate mixture. Add the flour. Whisk until the mixture is fully combined.
6. Divide the mixture between the two prepared muffin cups. You can fill them all the way to the top (you should have just enough mixture to fill them, but if you have extra, discard it).
7. Bake for 5 minutes, until the cakes have risen from their cups but still jiggle in the center just a bit. Place the muffin tin on a heat-safe surface and let the cakes cool for 1 minute.
8. In the meantime, find two dessert plates or appetizer plates with raised rims. Here’s the slightly tricky part—place the plates upside down over each of the cakes. While wearing oven mitts, securely grab both plates and the tin itself with both hands. Flip the whole thing and place the plate sides down on the counter. Gently lift up the tin and the lava cakes should release without trouble.
9. Garnish as desired (if using powdered sugar, place a small spoonful in a fine-mesh sieve and sprinkle the sieve over the plates). Serve at once! Leftover cakes will keep in the refrigerator, covered, for a few days (the texture will change, but should still be delightful).