Preheat oven to 325° F. Line bottom of either a 10-inch springform or 9 x 13-inch baking pan with parchment paper. Set aside.
In top of a double boiler set over simmering water on a medium burner, melt butter, vegetable shortening and unsweetened chocolate, stirring constantly. Set aside to cool 15 minutes, stirring occasionally.
In a large mixing bowl, mix eggs and salt on medium speed of an electric mixer about 3 minutes until light and fluffy. Add sugar and beat on medium speed until well-combined. Add vanilla and chocolate mixture and mix on low speed until combined.
Add flour and mix on low speed just until mixed. Do not over-mix.
Pour batter into prepared pan, spreading evenly, and bake in center of oven 30 to 35 minutes, or until edges are firm but center is still a bit soft. A wooden pick inserted in center will have some batter clinging. Remove pan to a metal rack and let cool 1 hour. Remove from pan.
These can be made ahead and refrigerated. Best to bring to room temperature before serving. Use a serrated knife dipped in hot water to cut these fudgy wonders.
Serve each piece with 1 1/2 tablespoons caramel sauce, 1 1/2 tablespoons hot fudge sauce, 2 heaping tablespoons Chocolate Whipped Cream, 3 chocolate chips, a teaspoon each confectioners' sugar and cocoa powder and 1/4 cup ice cream.Makes 12 Source: