Preheat oven to 350F.

Heat Italian dressing in a large skillet over medium heat.

Add sliced mushrooms and chopped onions to the skillet.

Cook and stir for 8 to 10 minutes, until onions are crisp-tender.

In a large bowl, stir together cottage cheese, chopped roasted poblano chiles, drained corn, crushed cracker crumbs, beaten egg, and 3/4 cup shredded cheese.

Spoon the vegetable mixture into cooked jumbo pasta shells.

Place the stuffed shells in a 13x9-inch baking dish sprayed with cooking spray.

Spoon any remaining vegetable mixture over the shells in the dish.

In a separate bowl, whisk together cream cheese spread and milk until blended.

Pour the cream cheese mixture over the stuffed shells.

Sprinkle the remaining shredded cheese over the top.

Cover the baking dish with foil.

Bake for 30 minutes, or until the shredded cheese is melted and the shells are heated through.