- Preheat oven to 400°F. Line medium baking sheet with sheet of parchment paper.
- Meanwhile, with small serrated knife, cut 1/2-inch slice off top of each tomato and discard. With grapefruit knife or same serrated knife, carefully cut around inside of each tomato to remove fleshy center. With spoon, scoop out juicy pulp and seeds and press through small sieve set over cup. Measure out 1/4 cup tomato water and reserve. Discard any remaining tomato water and seeds. Sprinkle tomato shells with 1/4 teaspoon table salt.
- Mix together Parmesan and bread crumbs in cup.
- Heat oil in large skillet over medium heat. Add spinach, remaining 1/4 teaspoon table salt, 1/4 teaspoon pepper, and reserved tomato water. Cook, stirring, until spinach is wilted and tomato water is evaporated, about 3 minutes. Stir in Parmesan mixture.
- Place tomatoes on prepared baking sheet and bake 6 minutes. Spoon spinach mixture into tomatoes, dividing evenly. Use back of spoon to line tomato shells with spinach, leaving centers empty. Crack 1 egg into cup and slip into tomato. Repeat with remaining eggs.
- Cover tomatoes with sheet of nonstick foil and bake 10 minutes. Uncover and bake until tomatoes are tender, egg whites are set, and yolks are slightly runny, about 10 minutes longer. Sprinkle with pepper and coarse salt and serve.
- Per serving: 1 stuffed tomato
The most efficient way to hollow out a tomato is with a grapefruit knife. It has an angled tip and a blade that is serrated on both sides. It's designed to easily separate the outer edge of citrus segments from the peel and membrane.