In a large pot, bring 4 quarts of water to a rolling boil over high heat. Once boiling, add 2 tablespoons of salt.

Add the spaghetti to the boiling water and cook according to the package instructions, typically 8-10 minutes. Reserve 1 cup of pasta water before draining.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the minced garlic and optional red pepper flakes, sautéing for 1-2 minutes.

Reduce heat to low and toss the drained spaghetti into the skillet with the sautéed garlic oil, mixing in reserved pasta water.

Stir in finely chopped parsley and freshly grated Parmesan cheese, adjusting salt and pepper to taste.

In a separate bowl, mix together 1/2 cup of softened unsalted butter, minced garlic, chopped parsley, and additional Parmesan.

Slice the Italian bread lengthwise and generously spread the garlic butter mixture on the cut sides.

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

Switch the oven to broil and cook the garlic bread for an additional 1-2 minutes for a crispy finish.

Plate generous portions of spaghetti garlic bread and garnish with extra cheese and parsley. Serve hot.