Spaghetti with Pistachio Pistou

Name: Spaghetti with Pistachio Pistou
Ingredients: 1 pound spaghetti; Salt; 1/2 cup pistachio butter; Freshly cracked black pepper; 1 clove garlic, grated (optional); 2 tablespoons finely sliced basil, plus extra for garnish; 2 tablespoons olive oil; 2 tablespoons room temperature unsalted butter; Good parmesan cheese for serving