Combine 2 baskets raspberries and 1/4 cup sugar in bowl. Mash berries coarsely with fork. Let stand until juices form, stirring occasionally, about 30 minutes.
04Cut cake crosswise into 8 pieces. Cut each piece into 3 strips. Line bottom of 3-quart trifle bowl with 8 cake strips, trimming to fit. Drizzle with 3 tablespoons syrup; spread with 2/3 cup curd, then half of mashed berries. Repeat layering. Top with remaining cake, syrup, and curd. Cover; chill overnight.
05Beat cream and 3 tablespoons sugar in bowl until peaks form; spread over trifle. Mound remaining berries in center.