PREHEAT oven to 350° F. Line 12-cup muffin tin with paper or foil liners.
COMBINE flour, baking powder and salt in large bowl; stir well.
BEAT sugar and butter in large mixer bowl until creamy. Beat in eggs one at a time, beating well after each addition. Beat in vanilla extract. Gradually beat in flour mixture alternately with milk until thoroughly combined. Spoon evenly into prepared cups, filling 2/3 full.
MELT ¼ cup morsels in microwave-safe bowl; stir until smooth. Drop about a teaspoon of chocolate into each filled cup and swirl gently with tip of knife.
BAKE for 20 minutes or until wooden pick inserted in cupcake comes out clean. Cool in pan on wire rack for 15 minutes. Transfer to wire rack to cool completely.
MELT remaining ¼ cup morsels. Spoon some frosting into a piping bag; top with a spoonful of melted chocolate. Pipe onto cupcakes, refilling bag as needed with additional frosting and chocolate. Garnish with sprinkles.