She has been very creative with substitutes based on what's in the fridge. Spinach has taken the place of basil, with no complaints (amazing what a little melted cheese can do)...
Place bread slices on cutting board. Use pastry brush to brush oil evenly over 1 side of each slice
Flip 1 slice over (oiled side down) and sprinkle with half of cheese. Place tomato slices on top and sprinkle with salt. Top with basil and remaining cheese. Place second slice of bread on top (oil on the outside).
Place sandwich in 10-inch nonstick skillet. Place saucepan lid on sandwich and press down firmly, then leave lid in place.
Heat skillet over medium heat and cook until bread is golden brown on bottom, about 4 minutes.
Use oven mitts to remove lid. Use spatula to flip sandwich over. Place lid back on sandwich and press down again. Cook until second side is golden brown and cheese is melted, about 2 minutes.
Turn off heat. Use spatula to transfer sandwich back to cutting board. Let cool for 2 minutes. Cut sandwich in half and serve warm.
2 (½-inch-thick) slices crusty bread
1 tablespoon extra-virgin olive oil
½ cup shredded mozzarella cheese
1 small tomato, sliced into circles
4 fresh basil leaves