Beat cream with sugar and vanilla in a small deep bowl with an electric mixer until it just holds stiff peaks.
Spread 1 heaping teaspoon cream onto each of 4 wafers. Arrange enough raspberries side by side (as close together as possible) on 1 cream-topped wafer to form an even layer. Stack 2 cream-topped wafers on a plate (cream sides up) and top with berry wafer, then carefully spread another teaspoon cream over berries. Top with last cream wafer and cover cream with remaining plain wafer. Frost top and sides of cake with remaining cream. Cover with an inverted bowl and chill at least 4 hours.
Serve cake with remaining berries and garnish with grated chocolate.