Heat oven to 350° F. Lightly coat four 5-ounce custard cups with vegetable cooking spray. Place the cups in a 9-by-9-inch roasting pan. In a medium skillet, combine the oil, ham, jalapeno, tomatoes, and scallions. Saute over medium heat until the vegetables are tender but not brown. Stir in the corn and divide among the custard cups. Top each with some of the cheese. In a medium bowl, whisk the eggs, then blend in the cream, milk, and salt. Pour over the vegetables in the cups. Place the roasting pan on the oven rack. Pour enough hot water into the pan to come halfway up the cups. Bake about 40 minutes or until a knife inserted in the center comes out clean.
*Or substitute 3/4 cup milk.