01 -
Heat olive oil in a big pan set over medium. Toss in the diced onion and stir every now and then until it turns golden. Mix in the crushed garlic for 30 seconds to a minute, just until you smell the aroma. Add the ground beef, breaking it apart as it cooks. Sprinkle with salt and keep stirring until the meat is browned. Pour in crushed tomatoes and water, then adjust salt to taste. Let it boil first, then bring the heat down, cover, and simmer for an hour, stirring here and there to meld the flavors. Mix in basil, turn off the heat, and set aside 120 milliliters (1/2 cup) of it for dipping later, if desired.
02 -
Fill a big pot with salted water and let it boil. Stir in the dried spaghetti and cook until it's firm but done (al dente). Drain it off and mix the cooked spaghetti with the prepared tomato sauce. Sprinkle in the Parmesan cheese and give it all a stir. Put parchment paper on a baking sheet. Spread the spaghetti on the paper, shaping it into a flat, single layer about 2.5 centimeters (1 inch) thick, making sure it's big enough for the sandwiches. Sprinkle more Parmesan evenly on top.
03 -
Combine the melted butter, garlic powder, and Italian seasoning in a small bowl and whisk until everything blends smoothly.
04 -
Slice your spaghetti layer into four parts. Spread butter over one side of a slice of bread, placing it, butter-side down, on the counter. Stack two mozzarella slices on top, then carefully place a spaghetti section above that. Add two more mozzarella slices over the spaghetti, and finish with another bread slice. Brush more of the butter over the top. Do the same with the other pieces to make four sandwiches.
05 -
Warm up a skillet over medium-low heat. Place one of the sandwiches on it. Cook with the pan covered, adjusting heat if necessary, until the bottom turns golden. Flip it gently, cover again, and cook until the other side is golden and the cheese melts. Repeat for all the sandwiches. Serve while warm and gooey.