CARAMEL: 3/4 cup firmly packed light brown sugar 3 tablespoons light corn syrup 3 tablespoons unsalted butter 1/4 teaspoon salt 1/4 cup heavy cream 1 teaspoon vanilla 1/2 teaspoon fresh lemon juice about 1-1/3 cups pecan halves (about 5 oz.) For the ganache: 1 cup heavy cream 12 oz. fine-quality bittersweet chocolate, chopped fine 1/4 teaspoon salt rum burnt-sugar sauce (recipe follows) as an accompaniment Make the base: Line the bottom of a buttered 8-1/2-inch springform pan, or tart pan with a removable fluted rim, with a round of wax paper and butter the paper. In small heavy saucepan melt the butter over moderate heat and add the cocoa powder, stirring until the mixture is smooth. Remove the pan from the heat, stir in the brown sugar, and let the mixture cool completely. Beat in the egg and stir in the flour, the pecans, the salt, and the vanilla. Spread the batter in the prepared pan and bake the base in the middle of a preheated 3 50° F. oven for 8 to 10 minutes, or until it is just firm to the touch and pulls away slightly from the side. Let the base cool in the pan on a rack for 5 minutes, or until it is just cool enough to handle but still warm. Remove the side of the pan, invert the base onto the rack, and discard the wax paper. While the base is still warm fit it gently into an 8-inch springform pan (it will slope up the side of the pan slightly) and let it cool completely in the pan on the rack. Make the caramel: In a small heavy saucepan combine the brown sugar, the corn syrup, the butter, and the salt, cook the mixture over moderate heat, stirring and washing down any sugar crystals clinging to the side of the pan with a brush dipped in cold water, until the sugar is dissolved, and boil it, undisturbed, for 8 to 10 minutes, or until a candy thermometer registers 280° F. Remove the pan from the heat and add the cream, the vanilla, and the lemon juice, stirring until the mixture is smooth. Let the caramel cool until it is room temperature. The caramel will thicken as it cools. While the caramel is cooling, beginning with the outer edge of the base, arrange enough of the pecan halves end to end in concentric circles to cover the base completely. When the caramel is cool, pour it onto the center of the pecan layer but do not try to spread it. The caramel will spread by itself to cover the pecans. Make the ganache: In a small saucepan bring the cream just to a boil and remove the pan from the heat. Whisk in the chocolate and the salt, whisking until the chocolate is melted completely, and let the mixture cool to room temperature. With an electric mixer beat the ganache until it just holds soft peaks, but do not overbeat it or it will become granular. Spread the ganache evenly over the caramel layer and chill the cake for at least 2 hours or overnight. The cake can be made up to 1 week in advance and kept covered with plastic wrap and foil and chilled. Run a thin knife around the edge of the cake, remove the side of the pan, and transfer the cake with a large spatula to a plate. Let the cake stand for 20 to 30 minutes, or until the ganache softens slightly, before serving. Serve the cake with the rum burnt-sugar sauce. Serves 12 to 20. RUM BURNT-SUGAR SAUCE 1-1/2 cups sugar 1/2 cup hot water 1/3 cup dark rum In a dry large deep heavy skillet cook the sugar over moderately high heat, stirring constantly with a fork, until it is melted completely and a deep golden caramel. Remove the skillet from the heat, into the side of it pour the water carefully, a little at a time, and cook the mixture over moderate heat, stirring, until the caramel is dissolved. Add the rum and simmer the sauce for 2 minutes. Pour the sauce into a heatproof pitcher or measuring cup and let it cool. The sauce will thicken as it cools. To thin the sauce slightly, set the pitcher in a saucepan of barely simmering water and stir the sauce until it reaches the desired consistency. Makes about 1-1/2 cups. dess 11