1. To make the filling: Put the butter in a 10- to 11-inch (25 to 28cm) skillet with 2-inch (5cm) high sides and set over medium-high heat. When the butter is melted, add the apples, cranberries, brown sugar, flour, cinnamon, nutmeg, vanilla, and salt. Toss until well blended. Continue cooking over medium-high heat, shaking the pan or gently stirring the contents with a wooden spoon, until the sugar is melted and the apples just begin to caramelize, about 5 minutes. Cover the skillet with a tight-fitting lid or a double layer of foil and reduce the heat to low. Continue to simmer, shaking the pan often, until the apples are tender when pierced with the tip of a knife, about 12 minutes longer.

2. To make the topping: Meanwhile, put the butter in a separate medium skillet and set over medium heat. When the butter is melted, stir in the 1/2 teaspoon cinnamon and add the granola. Cook, stirring constantly, until the granola is hot and evenly coated with the butter and cinnamon. Taste the granola and add more cinnamon if needed. Drizzle the maple syrup over the granola and cook, stirring, until hot and well blended, about 2 minutes. Set aside and keep warm until the filling is ready.

3. When the apples are tender, uncover the pan. If the apples have released a ton of juice (more than 1 cup/8 fl ounces/233 ml), increase the heat to high and boil briefly to reduce the liquid. Slide the skillet from the head and scatter the topping over the filling. Serve the crisp straight from the skillet hot, warm, or at room temperature. Accompany with a scoop of vanilla or cinnamon ice cream or a dollop of whipped cream, if desired.