Place the pine nuts in a dry skillet over medium heat. Stir frequently to ensure even toasting. After about 3-5 minutes, when they turn golden brown and release a warm nutty aroma, remove from heat immediately to prevent burning. Set aside to cool.
Bring a large pot of salted water to a boil. Add the fusilli pasta and cook according to package instructions until al dente, typically around 9-11 minutes. Drain the pasta using a colander, reserving about 1/4 cup of the pasta water to adjust the sauce consistency later if needed.
In a food processor or blender, combine fresh spinach leaves, basil leaves, toasted pine nuts (reserve a small handful for garnish), grated Parmesan cheese, minced garlic, and olive oil. Pulse until the mixture becomes a smooth, creamy pesto. If the pesto seems too thick, add a tablespoon or two of the reserved pasta water to loosen it up. Taste, then season with salt and pepper to your preference.
Transfer the drained fusilli to a large mixing bowl. Pour the prepared spinach pesto over the pasta and gently toss to coat each piece evenly. Add more pasta water if you want a silkier texture.
Dish out the Spinach Pesto Fusilli with Toasted Pine Nuts onto plates or a serving bowl. Sprinkle the reserved toasted pine nuts on top for an extra crunch and garnish with a little extra Parmesan if desired. Serve immediately for the freshest taste.
