Preheat oven to 350 degrees F. Place margarine in 9x13 inch pan and set in oven to melt; when margarine is melted, remove from oven.
In a mixing bowl, combine the flour, xanthan gum, 1-½ cups sugar, baking powder and salt. Add the vinegar and milk and mix until batter is smooth. Pour batter into the pan, then scatter the fruit evenly over the top. Sprinkle 2 tablespoons of sugar over the top.
Bake in preheated oven until cake is browned and fruit is bubbly, 50-60 minutes. Serve warm with a dollop of allergy free ice cream.
Notes
Nutrition Facts - Serving size: 1 piece (1/16th of the pan), calories: 223, total fat: 3 grams, saturated fat: 1 g, cholesterol: 0 g, total carbs: 33, fiber: 1.4 g, protein: 2.4 g