Preparation Preheat oven to 350°. Line 10-cup ovenproof glass bowl or 10-cup metal bowl smoothly with foil. Spray foil with nonstick spray. Combine dark rum and instant coffee in small bowl or ramekin; stir to dissolve coffee. Combine chocolate chips and butter in large bowl. Set bowl over saucepan of simmering water. Stir until chocolate and butter are melted and smooth. Remove bowl from over water. Using electric mixer, beat in sugar, then coffee mixture. Beat until mixture cools to lukewarm, about 3 minutes. Beat in eggs 1 at a time. Transfer batter to foil-lined bowl. Bake cake until top is cracked and dry and tester inserted into center comes out with some moist batter attached, about 1 hour 5 minutes. Cool cake in bowl on rack 15 minutes (center of cake will fall). Press edge of cake firmly to level with center of cake. Refrigerate cake uncovered until cold, at least 6 hours and up to 2 days. Invert bowl with cake onto platter, allowing cake to fall onto platter. Lift off bowl; peel off foil. Beat cream in large bowl until peaks form. Spread whipped cream all over cake, mounding cream in center. Cut into wedges and serve, or refrigerate up to 6 hours.
Preparation Preheat oven to 350°. Line 10-cup ovenproof glass bowl or 10-cup metal bowl smoothly with foil. Spray foil with nonstick spray. Combine dark rum and instant coffee in small bowl or ramekin; stir to dissolve coffee. Combine chocolate chips and butter in large bowl. Set bowl over saucepan of simmering water. Stir until chocolate and butter are melted and smooth. Remove bowl from over water. Using electric mixer, beat in sugar, then coffee mixture. Beat until mixture cools to lukewarm, about 3 minutes. Beat in eggs 1 at a time. Transfer batter to foil-lined bowl. Bake cake until top is cracked and dry and tester inserted into center comes out with some moist batter attached, about 1 hour 5 minutes. Cool cake in bowl on rack 15 minutes (center of cake will fall). Press edge of cake firmly to level with center of cake. Refrigerate cake uncovered until cold, at least 6 hours and up to 2 days. Invert bowl with cake onto platter, allowing cake to fall onto platter. Lift off bowl; peel off foil. Beat cream in large bowl until peaks form. Spread whipped cream all over cake, mounding cream in center. Cut into wedges and serve, or refrigerate up to 6 hours.