Cream butter; add 3/4 cup sugar, beating until light and fluffy. Add eggs, one at a time; beat well after each addition. Combine flour, baking powder, and salt; add to creamed mixture alternately with milk, beginning and ending with flour mixture. Stir in vanilla.
Spoon batter into greased muffin tins, filling half full. Bake at 350° for 15 to 18 minutes. Cool in pans 10 minutes; remove muffins to a wire rack, and cool completely.
Beat whipping cream until foamy; gradually add remaining sugar, beating until soft peaks form. Split cupcakes in half, and spread sweetened whipped cream over bottom half. Replace top half, and frost with Chocolate Frosting. Chill until ready to serve.