Blanch the broccoli, asparagus, peas, and bell pepper - Bring a large pot of heavily salted water to a boil over high heat. Fill a separate bowl with ice and water and set aside. Once the water comes to a boil, add the broccoli and boil for 30 seconds before adding the asparagus, peas, and bell pepper. Boil everything for 1 minute. Use a large slotted spoon to transfer vegetables to the ice water bath (reserve the pot of salted water to boil the penne) to stop cooking and lock in color. Once cool, drain in a colander and set aside.
Cook the penne - Return the pot of salted water to a boil over high heat. Add the penne and cook until al dente (approximately 2-3 minutes less than the recommended time). Drain and rinse with warm water. Set aside.
Sauté the garlic and squash - In a large pan with high sides, heat the olive oil and butter over medium-high heat. Add the garlic, zucchini, and yellow squash, and cook for 1-2 minutes stirring often. Add the cherry tomatoes and green onion and continue to cook for an additional 1-2 minutes. Stir often. Add the broth, half and half, and blanched vegetables - Add the vegetable broth and half and half (or full cream) to the pan. Increase heat to high and bring to a low boil. Add the blanched vegetables and cooked pasta to the pot and mix well to combine. Reduce heat to low.
Stir in the shredded parmesan - Stir in the shredded parmesan and season with salt and pepper to taste.
Serve - Serve garnished with fresh chopped parsley, fresh cracked black pepper, and fresh lemon juice, if desired.