HEAT oven to 400°F.
BROWN meat in large skillet; drain. Add VELVEETA and water; mix well. Cook until VELVEETA is melted, stirring frequently. Remove from heat. Stir in corn and salsa.
SPREAD 1/4 of the meat mixture onto bottom of 8-inch square baking dish sprayed with cooking spray; top with 2 tortillas. Repeat layers twice. Top with remaining meat mixture; cover.
BAKE 30 min. Uncover. Let stand 5 min. before serving.