No-Bake Raspberry Mousse Tartlets

chocolate wafer cookies, finely ground (about 1 1/4 cups of crumbs)

unsalted butter, melted

granulated sugar

fresh raspberries, divided (from 2 6-ounce clamshells)

lemon juice

unflavored gelatin

bar good quality white chocolate or bittersweet dark chocolate (not chips/baking pieces), shaved or very finely chopped

heavy whipping cream, divided

powdered sugar