85g3 oz fine-quality bittersweet or semisweet chocolate, chopped
85g3/4 stick margarine or butter, cut into pieces
57g1/4 cup ground pistachios
Instructions
Make the cake
Heat the oven to 300°F (150°C). Grease a 9-inch (22cm) springform pan with 4 teaspoons of the butter and line with baking parchment.
Soften the remaining margarine or butter. Finely grate the lemon peel. Split the vanilla bean and scrape out the seeds. Finely grind the almonds and pistachios together.
Beat the butter and the sugar until light and fluffy. Beat in the eggs, one at a time. Add the lemon peel and vanilla seeds, then fold in the nuts and sift in the flour.
Spoon the batter into the pan and bake for 45-60 minutes. The cake is ready when a skewer comes out clean. Leave to cool in the pan, then turn out.
Make the lemon topping
Grate the lemon peel and squeeze the juice. Halve the pistachios.
Mix the lemon juice with the sugar, boil until reduced to a syrup, then add the peel. Stir in the pistachios and pour over the cake.
Make the chocolate glaze
Melt chocolate with 1 tablespoon butter in a small heavy saucepan over very low heat, stirring. Remove from heat and add remaining 5 tablespoons butter, 1 tablespoon at a time, stirring until smooth.
Transfer the glaze to a bowl and chill, covered, until slightly thickened and spreadable, about 30 minutes.
Spread the glaze over cake with a small metal spatula. Sprinkle pistachios on the top and sides of the cake.