To prepare cream, combine the first 4 ingredients in a bowl, stirring well. Cover and chill.
Preheat oven to 400°.
To prepare tart, heat a 10-inch cast-iron skillet over medium-high heat. Coat pan with cooking spray. Add onion to pan; sauté 5 minutes. Add chile to pan; sauté 5 minutes. Remove casings from sausage. Add sausage to pan; sauté 2 minutes, stirring to crumble. Add corn and garlic to pan; sauté 5 minutes or until lightly browned. Remove corn mixture from pan.
Wipe pan dry with a paper towel. Recoat pan with cooking spray, and set pan aside.
Combine 2 cups water and salt in a saucepan over medium-high heat; bring to a boil. Gradually stir in the polenta; cook 5 minutes or until thick, stirring constantly. Remove from heat, and stir in 1 1/2 cups corn mixture. Pour polenta mixture into prepared pan. Sprinkle 1/4 cup cheese evenly over polenta mixture; top with remaining corn mixture. Sprinkle remaining 1/4 cup cheese over top.
Bake at 400° for 25 minutes or until lightly browned. Let stand for 5 minutes, and cut into wedges. Sprinkle with cilantro. Serve with chipotle cream.