Bring a large pot of salted water to a boil over high heat. Add the penne pasta and cook according to package instructions until al dente, about 10-12 minutes. Drain and set aside.

In a blender, combine ripe avocados, garlic, spinach, lemon juice, olive oil, salt, and pepper. Blend until smooth and creamy—about 30-45 seconds. Avoid over-blending.

In a mixing bowl, toss the cooked penne with the creamy avocado sauce until evenly coated.

Transfer to plates or a large serving dish and optionally top with grated Parmesan, halved cherry tomatoes, or fresh herbs. Serve immediately.