8 (1-ounce) squares semi-sweet baking chocolate, coarsely chopped
3/4 cup sugar
1/2 cup brewed coffee, room temperature
1 cup purchased glazed nut clusters or peanut brittle, chopped
Place oven rack in second from bottom position. Heat oven to 350°F. Line 8 1/2x4 1/2- or 9x5-inch baking pan with heavy-duty aluminum foil, extending foil over edges. Spray foil with no-stick cooking spray. Set aside.
Place butter and chocolate in metal or heat-proof bowl. Place bowl over pan of gently boiling water. Stir mixture until melted and smooth. Add sugar and coffee; stir until sugar is dissolved. Continue cooking until mixture is heated through and sugar is dissolved. Remove from heat.
Add eggs. Beat with whisk until well mixed. Pour mixture into prepared pan.
Place 13x9-inch glass baking pan onto oven rack. Set loaf pan in center of baking pan. Pour very hot water into bottom of glass baking pan to 1-inch depth. Bake 35-45 minutes or until chocolate mixture begins to puff slightly around edges and center is set. (Center may sink slightly during baking.)
Place onto cooling rack; cool 1 hour. Cover with plastic food wrap; refrigerate 3 hours or overnight.
Lift terrine out of loaf pan, using foil ends. Invert onto serving platter or cutting board; remove foil. Cut terrine into 1/2-inch slice, using knife that has been dipped into hot water and wiped dry. (Clean knife after cutting each slice.) Place slices onto individual serving plates.
Beat whipping cream in bowl at high speed until stiff peaks form. Top each serving with whipped cream; sprinkle with chopped glazed nut clusters.
Terrine can be made up to two days ahead; refrigerate until serving time.