Bring 4 quarts of water to a rolling boil in a large pot. Add 2 tablespoons of salt once boiling.

Add 12 ounces of spaghetti to the boiling water, stirring immediately to prevent sticking. Cook until al dente, typically 8-10 minutes.

In a large skillet, heat 3 tablespoons of olive oil over medium heat. Add 4 minced garlic cloves and red pepper flakes if using. Sauté for 1-2 minutes.

Toss the drained spaghetti into the skillet with the garlic oil. Gradually add reserved pasta water, stirring until creamy.

Stir in 1/4 cup of chopped parsley and 1/2 cup grated Parmesan cheese. Season with salt and black pepper to taste.

In a small bowl, mix 1/2 cup softened unsalted butter, 2 minced garlic cloves, 1/4 cup parsley, 1/4 cup Parmesan, and 1/4 teaspoon garlic powder.

Slice 1 loaf of Italian bread lengthwise. Spread the garlic butter mixture generously on the cut sides.

Preheat the oven to 375°F (190°C). Place the buttered bread halves on a baking sheet and bake for 10-12 minutes.

Broil for an additional 1-2 minutes for extra crispiness, monitoring closely to prevent burning.

Remove from oven and allow to cool slightly. Cut into pieces and serve with spaghetti.