Combine 1/2 cup sugar and sliced guava in a small mixing bowl; toss lightly to coat well. Set aside.
Preheat oven to 350°. Place butter in a 2-quart casserole; place in oven until butter melts. Remove from oven, and set aside.
Combine remaining sugar, flour, baking powder, and salt in a small mixing bowl; add milk, and stir just until dry ingredients are moistened.
Carefully pour batter over melted butter in casserole. Spoon sugared guava evenly over top of batter. Bake at 350° for 1 hour. (Batter will rise up over fruit, and become crisp brown.) Spoon into individual serving dishes, and serve with whipping cream. Serve immediately.