1 cup soy sauce
1 cup brown sugar
1/2 cup white sugar
1 1/2 cups milk
Preheat oven to 350 degrees F (175 degrees C).
In a large saucepan combine soy sauce, brown sugar, sugar and milk. Bring to a boil, reduce heat to medium-low, and simmer until mixture thickens, about 15 minutes. Remove from heat and stir in vanilla. Pour mixture into prepared 5x9x2 inch loaf pans.
Bake 20 to 25 minutes in the preheated oven, or until a toothpick inserted into the cake comes out clean. Cool completely before removing from pans. Refrigerate remaining peach preserves and peach preserves to cool while topping. Serve warm.