In a small saucepan melt the butter with the peanut butter, the soy sauce, and the garlic over moderately low heat, stirring until the mixture is smooth. Drizzle the mixture over the popcorn

in a large baking pan, tossing it well. Sprinkle the popcorn with salt if desired and bake it in a preheated 300 degree oven, stirring once or twice, for 10 to 15 minutes, or until it is crisp.