Begin by making your homemade basil pesto. In a food processor, blend fresh basil leaves, garlic, nuts, and Parmesan cheese. Slowly drizzle in ⅓ cup of olive oil until smooth and creamy. Taste and adjust seasoning as needed. Set aside.

In a large pot, bring water to a boil and add a pinch of sea salt. Add 12 ounces of spaghetti and cook according to package instructions until al dente, about 8 to 10 minutes. Reserve 1 cup of pasta water before draining.

In a large skillet over medium heat, combine the warm drained spaghetti with the prepared basil pesto and pour in ½ cup of reserved pasta water. Toss to coat evenly.

If the sauce is too thick, add more reserved pasta water to reach desired consistency. Warm the pasta over low heat for a few minutes, stirring and seasoning with black pepper and sea salt.

Serve the pesto pasta in bowls, garnishing generously with freshly grated Parmesan cheese and basil leaves. Enjoy warm.