Preheat oven to 350 degrees 4 F. In a large bowl, combine flour, powdered sugar, ground almonds, butter, and cocoa powder. Beat with an electric mixer until combined. Knead gently with hands until mixture comes together. Press dough onto the bottom and up the side of an ungreased 9- or 9 1/2-inch fluted square or round tart pan that has a removable bottom or a 9-inch pie plate.
Bake for 12 to 14 minutes or until crust is slightly puffed. Cool in pan on a wire rack.
In a medium saucepan, combine whipping cream, the 12 ounces chocolate, and the granulated sugar. Cook over medium heat just until chocolate is melted, stirring occasionally. Transfer to a medium bowl; whisk in strawberry jam. Cover and chill about 1 hour or until mixture is cooled and slightly thickened, stirring occasionally.
Beat cooled chocolate mixture about 30 seconds or just until the color lightens slightly. Pour into crust, spreading evenly. Cover and chill about 2 hours or until firm.
Prepare Whipped Almond Mascarpone. Using a small sharp knife, gently loosen edge of crust from side of pan. Remove side of tart pan. Spread the whipped mascarpone over top of tart. If desired, sprinkle each serving with the chocolate shavings. Makes 10 servings.
Whipped Almond Mascarpone
In a medium bowl, combine mascarpone cheese, sugar, whipping cream, and almond extract. Beat with an electric mixer on medium speed until smooth. Beat on high speed until mixture is thick and holds firm peaks.