Sauté ham and green onions in a large nonstick skillet over medium heat 5 minutes or until ham is brown and any liquid evaporates.
Brush bottom of pie shell evenly with mustard; sprinkle with 1/2 cup mozzarella cheese. Spoon ham mixture evenly over cheese, and top with single layer of sliced tomatoes.
Beat egg and half-and-half with a fork until blended; pour over tomatoes. Sprinkle evenly with basil, pepper, and remaining 1/2 cup cheese.
Bake on lowest oven rack at 425° for 20 to 23 minutes or until lightly browned and set. Cool on a wire rack 20 minutes. Cut into wedges to serve; garnish, if desired