Heston Blumenthal's Popping-Candy Chocolate Cake

(borrowed from ChubbyHubby.net and converted to U.S. measurements)

For the popping-candy base

3 ounces whole hazelnuts

1.5 ounces milk chocolate

2 teaspoons mixed spice to taste (ginger, cinnamon, nutmeg, cardamom, pepper, etc.)

3.5 ounces popping candy

For the chocolate mousse

12½ ounces dark chocolate

1¾ cups double cream

Pinch of salt

For the chocolate glaze

¾ ounce chocolate (same type as for the mousse)

½ cup water

8 whole coffee beans

Two pinches of salt

2½ ounces cocoa powder

2½ ounces unrefined golden caster sugar

To make the base, preheat the oven to 350 degrees Fahrenheit, and roast the hazelnuts for about 10 minutes until lightly colored. Blend to a paste in a food processor, and then set aside. Melt the milk chocolate in a bain-marie (a large basin over a saucepan of simmering shallow water; take care that the water does not touch the basin), and stir in the mixed spice and popping candy. Next, fold in the hazelnut puree. Place a 6-inch ring mold on a serving dish, and gently press in the base mixture to a depth of about a half-inch. Refrigerate for at least two hours, until hard.

To make the mousse, chop the chocolate into small pieces, and place in a metal bowl. Bring ½ cup plus 1 tablespoon of the cream to a boil in a small saucepan. Pour it over the chopped chocolate, and stir extremely gently until all the chocolate has melted, watching carefully to ensure it doesn't take on a granular texture. Add the salt to taste. Once the chocolate cream has cooled to room temperature, lightly whip the remaining cream to soft peaks, but do not overwhip. Fold into the chocolate mix. Pour over the base in the ring mold, and place in the fridge to set for two hours.

To make the glaze, chop up the chocolate, and set aside. Place the water, coffee beans, and salt in a pan, whisk in the cocoa powder, then set over medium heat and simmer for about three minutes. Meanwhile, put the sugar in a small pan and melt over medium heat. Unrefined sugar will caramelize quickly, so keep an eye on it; when it does, pour over the coffee and cocoa mix, and stand back, as it will bubble and spit. Beat in the chopped chocolate and, when melted, pass through a fine sieve. When cool but still liquid, pour over the mousse to your preferred depth and return the cake to the fridge to set.

To serve, run a hot knife around the inside of the ring before removing the cake. When slicing it, again make sure the blade of the knife is nice and hot.