Preheat the oven to 350 degrees F. Generously grease a 9 x 13 casserole dish and set aside.
Prep the veggies: trim the snap peas, peel and coin the carrot, thinly slice the mushrooms, chop the peppers, chop the summer squash, halve the cherry tomatoes, and rinse & drain the corn.
Prepare the tortellini according to package directions. In the last minute of boiling the noodles, add in the sugar snap peas and carrots.
Meanwhile, add 2 tablespoons olive oil to a skillet. Over medium heat sauté the mushrooms, peppers, and summer squash until crisp tender.
Drain the tortellini, snap peas, and carrots and return to pot. Add in the sautéed mushrooms, peppers, and summer squash. Add in the cherry tomatoes and can of corn.
In a small pot (or use the same skillet you used to sauté the veggies if it will work), melt the butter over medium-heat.
Whisk in the flour until a paste is made. Slowly whisk in the broth and stir until completely smooth. Then gradually, whisk in the milk and stir until smooth. (Add broth and milk slowly to allow the sauce to thicken). Add the garlic salt, pepper, and dried basil. Cook and stir until the mixture is thick and bubbly.
Add in the cream cheese and stir until smooth and the sauce is thickened.
Pour the sauce over the veggies and tortellini. Transfer the mixture to the prepared 9 x 13 casserole dish.
Cover the dish with foil and bake for 25 minutes. Remove the foil, add the mozzarella and parmesan cheese and broil for 2-3 minutes watching carefully until the cheese is melted on top.