Heat oven to 375°F.
Heat butter in large nonstick skillet with ovenproof handle. Add carrot, celery, pepper, onion; saute 3 minutes or until slightly softened. Remove from heat.
Stir together eggs, pineapple with its syrup, milk and mustard in large bowl until blended. Stir in bread, ham, cheese and cooked vegetables. Pour into skillet; use spatula to level off top.
Bake in 375°F oven 40 minutes or until set and golden.