Drain spinach well, pressing between layers of paper towels. Set aside.
Sauté sliced onions in hot oil in a large nonstick skillet over medium heat 5 minutes.
Stir in brown sugar; cook, stirring occasionally, 20 minutes or until onions are caramel colored. Reserve 1/4 cup onions. Spoon remaining onions evenly into 6 (6-ounce) custard cups coated with cooking spray; sprinkle evenly with Gorgonzola cheese.
Beat cream cheese with an electric mixer until smooth. Add egg and next 5 ingredients, beating just until blended. Stir in spinach. Spoon evenly over cheese in custard cups.
Place cups in a 13- x 9-inch pan. Add hot water to pan to a depth of 1 inch.
Bake at 350° for 30 to 40 minutes or until almost set. Remove cups from pan. Let stand 10 minutes; unmold, and top with reserved onions.
*1 (4-ounce) package crumbled blue cheese may be substituted.
Original recipe with half-and-half, more cheese, and oil: Calories 265 (70% from fat); Fat 21g (sat 11g); Chol:159mg.