1 750-ml bottle pink champagne or sparkling rosé, chilled
2 tbsp. unflavored powdered gelatin
1 1⁄2 cups sugar
Canola oil, for greasing
40 fresh raspberries (about 8 oz.)
2 small bananas, cut into coins
1. Pour 1⁄2 cup champagne into a bowl; sprinkle in gelatin; let sit 5 minutes. Heat remaining champagne and sugar in a 1-qt. 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-oz. ramekins. Pour 1 1⁄2 tbsp. 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.