Step 1: Prepare the Ingredients

1. Cook the Pasta: In a large pot, boil salted water and cook the spaghetti until al dente according to package instructions. Drain and set aside.
2. Chop and Prep: Mince the garlic, chop the onion, and prepare the spinach and basil by rinsing and drying them.

Step 2: Make the Green Sauce

1. Sauté Aromatics: In a large skillet, heat olive oil over medium heat. Add the garlic, onion, and jalapeño (if using), sautéing until they’re soft and fragrant.
2. Blend the Sauce: Transfer the sautéed mixture to a blender or food processor. Add the spinach, basil, cream, salt, and pepper. Blend until the sauce is smooth and has a vibrant green color. You may need to add a splash of water or pasta water to achieve your desired consistency.

Step 3: Combine Pasta and Sauce

1. Toss the Pasta: Return the green sauce to the skillet, add the cooked spaghetti, and toss until the pasta is well-coated in the sauce.
2. Adjust Seasoning: Taste the dish and adjust salt, pepper, or add more cream if needed for extra richness.