1. Pour 1/2 cup Champagne into a bowl; sprinkle in gelatin; let sit 5 minutes. Heat remaining Champagne and sugar in a 1-quart saucepan over medium-high heat, stirring occasionally, until sugar dissolves. Remove from heat; stir in gelatin mixture. Let cool for 10 minutes.

2. Grease eight 4-ounce ramekins. Pour 1 1/2 tablespoons Champagne mixture into each mold; chill 30 minutes. Put 5 raspberries into each mold; add enough Champagne mixture to half-cover the berries. Chill until set, about 30 minutes. Arrange 4 banana slices, overlapping them slightly, in each mold. Add remaining Champagne mixture; chill until completely set, at least 4 hours.

3. To serve, slide a knife along edge of each mold; set molds in a bowl of hot water for 5 seconds. Invert molds onto plates.

SERVES 8