Heat oven to 375°F. Spray 2-quart casserole or 8-inch square pan with cooking spray. Sprinkle chiles and tomatoes evenly in casserole.
In medium bowl, beat remaining ingredients except salsa with wire whisk until blended. Pour over chiles and tomatoes.
Bake uncovered 35 to 40 minutes or until knife inserted in center comes out clean. Serve with salsa.