Bring a large pot of water to a boil. Add a good pinch of salt and the pasta.
Cook until the pasta is al dente according to the package instructions. Reserve about 1/2 cup of pasta water and then drain the pasta. Drizzle a little olive oil over the pasta to prevent sticking.
Heat olive oil in a large, deep skillet over medium heat. Add the sliced garlic and cook for about 1 minute until fragrant.
Add the squash, zucchini, asparagus, cherry tomatoes, bell pepper, and red onion. Season with salt, a pinch of red pepper flakes if using, and a few grinds of black pepper. Sauté for 3 to 4 minutes until the vegetables start to soften.
Add the peas and cook for another minute. Toss in the cooked pasta, grated Parmesan, and fresh lemon juice. Stir to combine and add a splash of reserved pasta water if the sauce seems dry.
Finally, fold in the fresh basil leaves. Taste and adjust seasoning if needed, then serve warm.