Preheat oven to 400°.
To prepare topping, remove 1 chile and 2 teaspoons sauce from can; reserve remaining chiles and sauce for another use. Coarsely chop 1 chile.
Place potatoes in a saucepan; cover with water. Bring to a boil; cook 15 minutes or until very tender. Drain. Place potatoes, chopped chile, 2 teaspoons adobo sauce, milk, salt, and 1/4 teaspoon pepper in a large bowl. Beat with a mixer at medium speed until smooth.
To prepare filling, cook beef in a large nonstick skillet over medium-high heat until browned, stirring to crumble. Remove from pan; drain.
Heat pan coated with cooking spray over medium-high heat. Add onion, carrot, and garlic; sauté 8 minutes or until tender. Return beef to pan; stir in peas and remaining ingredients. Cook 2 minutes.
Spoon beef mixture into a 3-quart casserole; top with sweet potato mixture, spreading evenly. Bake at 400° for 30 minutes or until thoroughly heated.