In a large pot, fill with 4 quarts of water and bring to a rolling boil over high heat. Add 2 tablespoons of salt.

Add spaghetti to the boiling water. Cook according to package instructions, typically around 8-10 minutes, until al dente.

Carefully pour the spaghetti into a colander to drain the water, reserving about 1 cup of starchy pasta water.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Finely mince garlic and sprinkle in optional red pepper flakes. Sauté for 1-2 minutes.

Add the drained spaghetti into the skillet, tossing to coat in garlic oil. Gradually add reserved pasta water to achieve desired sauce consistency.

Stir in a handful of freshly chopped parsley and 1/2 cup of grated Parmesan cheese. Mix thoroughly, adjusting seasoning as needed.

In a mixing bowl, combine 1/2 cup of softened unsalted butter, 3 minced garlic cloves, and more parsley. Blend to create a garlic spread.

Slice the Italian bread lengthwise and spread the garlic butter mixture on both halves evenly.

Preheat oven to 375°F (190°C). Place the bread on a baking sheet, cut sides up, and bake for 10-12 minutes until golden-brown.

For an extra crispy finish, place bread under the broiler for about 1-2 minutes while keeping a close watch.

Remove from oven, let cool, slice into portions, and serve spaghetti warm alongside crispy garlic bread.