Begin by preparing the vegetables. Wash them thoroughly and cut each into uniform pieces. Slice the zucchini and yellow squash into half moons, cut the carrot into thin rounds, halve the grape tomatoes, and slice the red onion into strips.

In a large pot, bring salted water to a boil. Cook the penne pasta according to the package directions, ensuring it reaches an al dente texture. Before draining the pasta, reserve a small amount of the cooking water for later use.

While the pasta cooks, heat olive oil in a large skillet over medium heat. Add the sliced carrots and onions, sautéing them for 1-2 minutes. Then, add the zucchini and yellow squash and continue to cook for an additional 1-2 minutes.

Next, incorporate the minced garlic, halved grape tomatoes, and frozen peas into the skillet. Season the mixture with salt, black pepper, and dried oregano, allowing it to sauté for another 1-2 minutes before turning off the heat.

To finish, add the butter and freshly squeezed lemon juice to the skillet, stirring until everything is well combined. Combine the cooked pasta with the sautéed vegetables in the skillet, or transfer the mixture to a large serving bowl. Sprinkle grated Parmesan over the top and stir in a bit of the reserved pasta water to help coat the ingredients. Serve with freshly chopped parsley, if desired, and enjoy!