PREHEAT oven to 375º F. Grease 9-inch-round baking pan.
BRING onions, water and salt to a boil in medium saucepan or skillet. Cook over medium heat, stirring occasionally, for about 10 minutes or until onion is softened. Allow to cool.
BEAT butter and cheese until well mixed. Add eggs, one at a time, beating well after each addition. Add onion mixture; mix well. Beat in corn meal alternately with evaporated millk. (Mixture will be soupy.) Pour into prepared pan.
BAKE for 40 to 45 minutes or until wooden pick inserted in center comes out clean. Cut into wedges and serve warm.