Position rack in lower third of oven and preheat to 425F for 10 minutes. Add margarine and a 5-second spray of cooking spray to a 9-inch or 10-inch pie pan or iron skillet; place in oven to melt margarine.
In a large bowl, whisk together Egg Beaters and egg white. Then, whisk in flour, milk, vanilla, sugar, nutmeg and salt. Stir in blueberries. Pour batter into preheated pan and return to oven; bake for 15 to 20 minutes, until edges are puffed and golden brown. Remove from oven; squeeze juice from half fresh lemon over entire surface of pancake and sift confectioner’s sugar over all. Cut into wedges and serve hot.