Combine milk, instant pudding mix, and vanilla extract in a large bowl. Beat mixture with a hand mixer for 2 minutes, or until it thickens. Place mixture in refrigerator for 15 minutes. Spoon filling into a pastry bag fitted with a medium-size plain tip. Fill cupcakes with vanilla pudding filling by inserting tip into top of cupcake and squeezing a couple of tablespoons of filling into each cupcake.
Heat cream in a small heavy saucepan over medium heat until bubbles appear around the edges. Remove from heat, add chocolate morsels to pan, and whisk until smooth. Spoon or drizzle glaze over cupcakes, or dunk the tops into the glaze. Refrigerate until set, at least 1 hour, before serving. Sprinkle with powdered sugar.