Make crust: Preheat oven to 375ºF. In a food processor, pulse wafers and sugar until ground. With motor running, add butter until clumps form. Press into a 9-inch tart pan. Bake 10 minutes; cool on a wire rack.
Make filling: Warm cream on medium heat until it just boils. Remove from heat and add butter and chocolate. Let stand 5 minutes, then stir until smooth. Strain raspberries; pat dry with paper towels. Cover tart shell with a layer of raspberries. Pour filling over. Chill until set, 2 hours.
Make topping: Warm all ingredients on low heat until melted, stirring often. Drizzle on tart. Chill 5 minutes.