Heat oven to 400. Grease pie plate, 10 x 1 1/2". Mix tuna, cheeses, onions and pimiento in plate. Beat trmaining ingred. 15 sec. In blender on high or 1 minute with hand beater. Pour into plate. Bake until knife inserted between center and edge comes out clean, 35-40 minutes. Cool 5 minutes. Serve with sliced tomatoes. Serves 6-8. Variations: Seafood pie: Substitute 1 pkg (6 oz.) frozen crabmeat or shrimp, thawed, drained, for the tuna. High Altitude: Bake 45-50 minutes.