Preheat oven to 350*F.
Prepare apples by using an apple corer, small knife, melon baller, and/or spoon to remove the stem and scoop out the seeds, leaving a ½-inch at the bottom of the apple intact and creating a hole that's a little less than 1 inch wide.
Measure the granola into a medium bowl, and use the back of a spoon to work the peanut butter in until it's evenly incorporated. Use more or less peanut butter depending on your preference (I use 3 tablespoons when I make this recipe).
Place apples in an 8-inch square baking dish and carefully pour hot water into the bottom of the dish. Cover dish with foil and bake for 30 minutes. Remove foil and bake for an additional 20 to 25 minutes, or until apples are to your desired tenderness and skin looks wrinkly. (Test by inserting a sharp knife into the center of an apple where it touches the granola. There should be little to no resistance. Certain varieties of apples and larger apples will take longer to soften. If apples are still too firm at the end of the baking time, you may want to recover them with foil before cooking any longer so that the granola doesn't get too dark.)