Prepare potatoes with milk according to package directions.
Stir in 3/4 cup cheese, broccoli, and next 3 ingredients. Spoon evenly into 4 lightly greased (8-ounce) custard cups.
Beat whipping cream at medium speed with an electric mixer until stiff peaks form; fold in remaining 3/4 cup cheese. Spread mixture evenly over potato mixture.
Bake at 350° for 20 minutes.