Preheat oven to 350°F. Combine milk, egg yolks, TABASCO® Sauce and baking powder in a small bowl and beat with a fork. In a larger bowl, beat egg whites until stiff but not dry. Fold yolk mixture lightly into egg whites.
Melt butter in a heavy, oven-safe 10-inch skillet over low heat. Pour egg mixture into skillet. As omelet cooks, slash it through with a knife to allow heat to penetrate lower layers.
When omelet is half done (after about five minutes), place skillet in oven and bake until top is set and lightly browned. Serve at once.
To serve, cut in four wedges, using two forks instead of knife to divide omelet. If desired, serve with a sprinkling of parsley, chives, or grated Parmesan cheese.
Makes 4 servings.