Preheat oven to 350 degrees. Line 10-inch quiche pan with crust. Heat nonstick pan with olive oil; saute onion and garlic until slightly brown. Spread onion mixture on crust and sprinkle cheese on top. Arrange tomato slices over cheese. Top with basil.
Combine milk, cornstarch, pepper, and eggs. Process in blender until smooth. Carefully pour over tomatoes. Bake 45 minutes or until a knife inserted near the center comes out clean. Let stand 10 minutes before serving.