Trim the asparagus and cut into 1-inch pieces, dice the yellow pepper into bite-sized chunks, cut the broccoli into small florets, and slice the zucchini into 1/4-inch half-moons. Mince the garlic cloves finely, dice the shallot, zest the lemon, and mince the basil and parsley. Grate the Parmesan cheese fresh (you'll notice a much smoother sauce this way compared to pre-shredded). Have all ingredients measured and ready before you start cooking.

Bring a large pot of water to a boil and add 1 1/2 teaspoons salt. Add the penne and cook for 11 minutes until al dente (the pasta should have a slight firmness when you bite it). Drain the pasta in a colander but do not rinse it—the starch on the pasta helps the sauce adhere better.

While the pasta cooks, heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the asparagus, yellow pepper, and broccoli, cooking for 2-3 minutes until they just begin to soften but remain crisp. Add the zucchini and cook for another 1-2 minutes, then transfer all vegetables to a clean bowl. The vegetables will continue to soften slightly when mixed with the warm sauce, so keeping them just slightly undercooked here ensures the final dish has great texture.

In the same skillet, melt the butter over medium heat and add the diced shallot and minced garlic. Cook for about 2 minutes, stirring occasionally, until fragrant and slightly softened. Stir in the lemon zest, then pour in the vegetable broth and simmer for 4-5 minutes to allow the broth to reduce slightly and the flavors to concentrate. The lemon zest will release its oils and create a bright, fresh base for the sauce.

Remove the skillet from heat and stir in the heavy cream and 2 tablespoons of lemon juice. Return to medium heat and add the cooked pasta from Step 2, the sautéed vegetables from Step 3, and the peas. Gently fold everything together for about 1-2 minutes to warm through. Then stir in the freshly grated Parmesan cheese, the remaining 1 tablespoon of lemon juice, the tomatoes, and the minced basil. Season with 1/2 teaspoon salt, 1/4 teaspoon black pepper, and 1/8 teaspoon nutmeg, stirring gently to combine.

Divide the pasta primavera among serving bowls or plates. Top each serving with a small amount of freshly grated Parmesan cheese, a sprinkle of fresh parsley, and a pinch of red pepper flakes for a subtle kick. Serve immediately while the pasta is still warm and creamy.