01 -
In a large saucepan, drizzle olive oil over medium heat. Add the diced onion and cook, stirring occasionally, until lightly golden. Add the crushed garlic and cook until just fragrant, 30 seconds to 1 minute. Stir in the ground beef, breaking it into small pieces with a spoon. Season with salt and cook, stirring often, until browned. Pour in the crushed tomatoes and water. Season with additional salt if needed. Bring to a boil, then reduce heat to a simmer, cover, and cook, stirring occasionally, for 1 hour to blend the flavors. Stir in the basil and remove from heat. Set aside 1/2 cup (120 milliliters) of the sauce for dipping if desired.
02 -
Bring a large pot of salted water to a boil. Add the dried spaghetti and cook, stirring occasionally, until just al dente. Drain the spaghetti and toss with the prepared tomato sauce. Stir in the grated Parmesan cheese. Line a baking sheet with parchment paper. Pour the spaghetti onto the parchment-lined baking sheet and spread into a single, 1 inch (2.5 centimeter) thick layer, large enough to fit into each of the sandwiches. Sprinkle additional Parmesan cheese over the top in a thin layer.
03 -
In a small bowl, whisk together the melted butter, Italian seasoning, and garlic powder to blend.
04 -
Cut the slab of spaghetti into four pieces. Brush one slice of bread with the seasoned butter and place it butter-side down on the work surface. Top the bread with two thin slices of mozzarella. Carefully place a slab of the spaghetti on top. Cover with another two slices of mozzarella and a second slice of bread. Brush the top with more seasoned butter. Repeat with the remaining spaghetti and bread to make four sandwiches in total.
05 -
Heat a skillet over medium-low heat. Place one assembled sandwich on the hot skillet. Cover and cook, adjusting the heat as needed, until the bread is golden. Flip carefully, cover again, and cook the other side until the bread is golden and the cheese is melted. Repeat with the remaining sandwiches. Serve warm.