Combine 1 quart of the milk in a saucepan with the sugar, and cook over a low heat, stirring from time to time, until the mixture turns golden. Meanwhile, stir the soda into the remaining quart of milk in a saucepan. Add the cinnamon stick, and bring to a boil. Discard the cinnamon. Add the hot milk to the caramel mixture very gradually, stirring constantly. When all the milk in incorporated, place over a low heat, and cook very slowly until the mixture is thick. Cool slightly; then pour into a glass serving bowl, and chill. Variations: Cajeta Envinada (Milk candy with wine): Follow the directions for Cajeta de Leche, omitting the cinnamon. When it is just about cooked, stir in 1 cup of sweet sherry, Madeira, or muscatel, and continue cooking until the wine has been absorbed. Cajeta de Almendra Envinada (Milk Candy with Wine and Almonds). Pulverize 1/4 cup whole, blanched almonds in an electric blender. Combine with the milk and soda, omit the cinnamon, and bring to a boil. Then add to the caramel mixture as directed in the recipe for Cajeta de Leche. When almost cooked, stir in 1 cup of sweet sherry, Madeira, or muscatel, and continue cooking until the wine has been absorbed. From: The Complete Book of Mexican Cooking Shared By: Pat Stockett