Heat oven to 350°F. Grease 8-inch square (2-quart) baking dish.
Melt 2 tablespoons butter in large nonstick skillet over medium-high heat. Add potatoes, mushrooms and onions; cook 5 to 8 minutes or until tender, stirring occasionally. Stir in asparagus and roasted peppers. Spoon into greased baking dish.
In medium bowl, combine eggs, half-and-half, lemon juice, salt and marjoram; beat well. Pour over vegetables in dish. Cover with foil. Bake at 350°F. for 1 hour.
In small bowl, combine all topping ingredients; mix well. Uncover baking dish; sprinkle with crumb mixture. Bake uncovered for an additional 10 to 15 minutes or until casserole is set and top is golden brown.