Step 1

Heat the oven to 375º F, and butter a 9-inch cake pan. Line the base of the pan with parchment, and butter that, too.

Step 2

Chop the chocolate and melt it in a double boiler (I use a metal bowl over a simmering pan of water), stirring continuously. Once it begins to melt, add the butter, and keep stirring until both are fully melted. Add the sugar, stir to combine, and set aside to cool slightly.

Step 3

Add the eggs one at time, mixing very well after each. Mix in the flour. At this point your batter should be super smooth.

Step 4

Pour batter into the prepared cake pan and bake for about 25 minutes -- or, as Molly says, until the center of the cake looks set and the top is shiny and a bit crackly-looking.

Step 5

Let the cake cool in its pan on a rack for 10 minutes; then carefully turn the cake out of the pan and revert it, so that the crackly side is facing upward. (The cake will deflate slightly as it cools.) Allow to cool completely before you serve.

Step 6

Serve in wedges at room temperature with whipped cream -- or nothing at all.

Step 7

Combine the lemon peels and the cream in a heavy saucepan, and bring to just under a boil.

Step 8

Before it comes to a boil, take the cream off the heat, cover, and let steep for 30 minutes.

Step 9

Cool completely, strain, chill, and then whip to soft peaks. Alternatively, if you don't have much time, you can grate lemon peel into cold cream before you whip it.