1. Preheat the oven to 325°F. Melt the chocolate and butter gently over low heat in a heavy-bottomed saucepan.

2. Add the sugar and vanilla to the pan off the heat, and let it cool a little.

3. Beat the eggs into the pan with the ground almonds and walnut pieces. Turn into a 9-inch square baking pan or, most senslbly, use a foil one.

4. Bake for 25–30 minutes, by which time the top will have set but the mixture will still be gooey. Once cooler, cut carefully, four down, four across, into 16 squidgy-bellied squares.

For the Sauce

1. Break up the chocolate and put into a heavy-based saucepan.

2. Add the remaining ingredients, then place the pan over a gentle heat and let everything melt together.

3. Once everything has melted, stir well, take off the heat, and pour into a jug to serve.