Prepare Cashews (If Using): Ensure cashews are soaked (min. 2 hours), then drain well.
Cook Pasta: Boil pasta in generously salted water until al dente according to package directions. Important: Reserve about 1 cup of pasta water before draining. Drain pasta and set aside.
Prepare Zucchini: Wash, trim, and chop zucchini into roughly 1/2-inch pieces/slices.
Sauté Zucchini: Heat ghee/oil in a large skillet over medium heat. Add zucchini, 1/2 tsp salt, and 1/4 tsp pepper. Cook, stirring occasionally, until tender (about 8-10 minutes). Avoid significant browning.
Make Creamy Sauce (Optional): Transfer about 2/3 of the cooked zucchini to a blender. Add drained cashews, 1 tbsp lemon juice, and 1/2 cup reserved pasta water. Blend until very smooth. Add more pasta water (1 tbsp at a time) if needed to reach desired consistency. Taste and adjust salt.
Combine Sauce & Pasta: Pour blended sauce (if made) back into the skillet with remaining zucchini. If not blending, proceed with all sautéed zucchini in the skillet. Add cooked pasta. Toss gently over low heat until coated. Add more pasta water if dry. Simmer 1-2 minutes.
Add Fresh Herbs: Turn off heat. Stir in chopped fresh basil.
Serve: Taste and adjust seasoning (salt, pepper). Serve immediately, garnished with extra basil, lemon zest, or toasted seeds if desired.