In this salad, the hot pasta will wilt the spinach and soften the squash. Firm tofu, cut into cubes and cooked in a nonstick pan, can be used in place of shrimp.
In a large pot of boiling salted water, cook pasta according to package instructions. Drain pasta, transfer to a large bowl, and toss with squash, olives, spinach, lemon zest and juice, and 1 tablespoon plus 1 teaspoon of the oil. Season with salt and pepper.
In a large skillet, heat remaining 2 teaspoons oil over medium-high. Add shrimp and cook, stirring occasionally, until opaque throughout, about 3 minutes. Season with salt and pepper. Top pasta with shrimp.