Directions:

Preheat the oven to 350°F (gas-mark "4" or 175°C). Butter a 9-inch (23 cm) round cake pan and line it with a round of parchment paper cut to fit.

Cut the parchment paper to fit a round 9- or 10-inch baking pan that would be used for baking a layer cake. Butter and flour the pan. Cut the parchment in a 5" strip so you will have a rim of paper. Butter the paper. Line the bottom and the sides of the pan. Flour the paper.

Break the chocolate into small pieces (use the flat edge of a wide cook's knife or cleaver to make fast work of this). Melt the butter and chocolate in a double boiler over hot water.

Beat the egg yolks with half of the sugar.

Fold in the melted butter and chocolate mixture.

In a separate bowl, whip the egg whites with an electric mixer and gradually add the remaining sugar, as peaks form, until the mixture is fluffy and has high, stiff peaks.

Fold in the beaten egg whites, taking care to turn them gently into the chocolate mixture. The mixture should be poured carefully into to the pan.

Bake at 350 degrees F, until a wooden pick inserted into the centre comes out clean -- approximately 40 minutes. Please note that cakes of this type will collapse and resemble a pie, because no flour is used; this is normal, and creates the appealing density of this particular cake.

When slightly cooled, use a knife to separate the cake from the parchment paper "collar," and plate. Please note that this cake comes out quite sticky, so you might want to run your knife under hot water periodically, as you remove the parchment paper.

Serving suggestion: This flourless chocolate cake may be served warm (our preference) or cold, and topped with whipped cream. It is also nice sided with vanilla ice cream. The whole confection may be dusted with powdered icing sugar, and it's attractive to dust the whipped cream or ice cream lightly with cocoa.

Difficulty level: Moderate.