Find canned chipotle peppers in the Mexican food aisle. You can finely chop and freeze leftovers in a flattened zip-top bag. Break off a small chunk to add smoky heat to chilies, soups and taco meat.
Preheat oven to 375°. Cook sweet pepper and onion in hot oil in a 12-inch cast-iron oven-going skillet over medium-high heat for 4 to 5 minutes or until vegetables are just tender, stirring occasionally. Add garlic and cook and stir for 1 minute more.
Remove skillet from heat and stir in chipotle pepper and salt. Transfer mixture to a small bowl (don't worry if a little mixture remains in skillet). Arrange sweet potatoes in skillet, layering with pepper mixture as you go. In a small bowl, stir together cream and broth; pour over potato mixture in skillet. Sprinkle cheese over top.
Cover skillet with lid or foil. Bake 40 minutes. Remove lid or foil and bake 30 minutes more or until potatoes are tender and top is lightly browned. Let stand 5 to 10 minutes before serving.