Bring large pot of lightly salted water to a boil. Preheat oven to 350°F. Coat 13 x 9-inch glass baking pan with cooking spray; set aside. Add squash to boiling water and cook until tender, about 12 minutes.
Drain squash, transfer to large bowl and mash well. Add cream cheese, brown sugar, cinnamon and garam masala if desired; blend with hand mixer until smooth. Adjust seasonings to taste. Mix in half of the onions.
To assemble: Place 1/2 cup squash mixture along center of each tortilla, roll up tightly and arrange seam side down in prepared pan. Top with taco sauce then sprinkle with cheese.
Bake until heated through, about 10 minutes. Serve hot with remaining onions, tomato and lettuce.