THE BEST FLOURLESS CHOCOLATE CAKE

This cake is so easy to make yet impressive, insanely delicious, wheat free and totally bad for you.
NOTE: this HAS to chill for at LEAST 4 hours!

For batter

12 oz semisweet chocolate, chopped
1 1/2 sticks unsalted butter
4 large eggs
1/2 cup sugar

For sauce

(I didn't make the sauce, I just used a mesh strainer to sprinkle powdered sugar on it, then made whip cream.)

10-oz package frozen unsweetened raspberries, thawed
1/4 cup sugar

Accompaniment: unsweetened whipped cream

Preheat oven to 350°F. Butter a 9- by 2-inch round cake pan and line bottom with a round of wax paper. Butter paper and dust pan with flour, knocking out excess.

Make batter:

Melt chocolate and butter in a metal bowl set over a saucepan of simmering water, whisking until smooth.
Cool slightly.
Beat together eggs and sugar with an electric mixer until pale yellow, thick, and a ribbon forms when beaters are lifted, about 4 minutes with a standing mixer or 8 minutes with a handheld. Fold one fourth of egg mixture into chocolate mixture to lighten, then gently fold in remaining egg mixture.
Pour batter into cake pan and rap pan sharply on counter to eliminate air bubbles. Put cake pan in a hot water bath and place in middle of oven. Bake 45 minutes (top will be set, but a tester will not come out clean).
Remove cake from water bath and cool completely in pan on a rack. Run a thin knife around edge of cake and chill, covered, at least 4 hours and up to 12.

Make sauce:

Purée raspberries with sugar in a food processor or blender, then force through a fine sieve into a bowl. Chill until ready to serve.

Remove cake from pan:

Put cake pan directly on a burner at very low heat. Move pan around on burner to warm bottom, about 30 seconds, then shake pan to loosen cake. Invert cake onto a rack. Remove wax paper and invert cake onto a serving plate.
Bring cake to room temperature. Serve with sauce and whipped cream.
NOTES
Don't despair if the cake stubbornly refuses to come out of the pan. You may need to help it along by prying it out gently with the tip of a paring knife.
This cake is better if made a day ahead. Both cake and sauce keep 2 days, covered and chilled.