Cook potato slices in boiling, salted water to cover 13 minutes. Add beans, and cook 2 more minutes. Remove from heat; drain well.
Pulse bread slices in a blender or food processor 8 or 10 times or until bread is crumbly.
Place potato slices and lima beans in a greased 10-inch deep-dish pieplate; sprinkle with half of Gruyère and half of Parmesan. Top evenly with egg; sprinkle with remaining cheese, salt, and pepper. Pour cream around inside edge of pieplate; sprinkle evenly with breadcrumbs.
Bake at 475° for 10 minutes or until lightly browned.
