HEAT oven to 350°F.
MIX first 6 ingredients in large bowl until well blended. Add spinach, peppers and onions; mix well.
SHAPE into 9x4-inch loaf in 13x9-inch pan sprayed with cooking spray.
BAKE 45 min. Mix mustard and honey; brush onto meatloaf. Bake 25 to 35 min. or until done (165°F). Let stand 10 min. before slicing.