Heat olive oil in a large pot over medium heat. Add diced onion with a pinch of salt and red pepper flakes, cooking until soft and translucent. Stir in the garlic and cook just until fragrant.
Add squash, zucchini, grated carrots, sun-dried tomatoes, and Italian seasoning. Season lightly with salt and cook until vegetables begin to soften and slightly caramelize. This step deepens the overall flavor.
Pour in the stock and drop in the Parmesan rind. Bring the mixture to a gentle boil before adding the pasta. Cook until noodles are tender but still slightly firm.
Turn off the heat and stir in fresh spinach, heavy cream, and pesto. The spinach will wilt from the residual heat. Taste and adjust seasoning with salt and pepper as needed.
Ladle into bowls and top with a dollop of ricotta. Sprinkle freshly grated Parmesan and drizzle a bit of olive oil over the top. Finish with cracked black pepper and flaky salt.