Preparation

Make the cookie

• Position a rack in the center of the oven and heat to 325°F.
• In a heavy-duty 8-inch ovenproof skillet, melt the butter over medium-high heat. cook, swirling the pan often, until golden brown, 3 to 4 minutes. Transfer the butter and all the brown bits to a large bowl and let cool briefly. Set the skillet aside for later (no need to clean it).
• Add the two sugars to the brown butter, and whisk to combine. Whisk in the egg and vanilla. add the flour, cinnamon, salt, and baking soda, and stir to combine. Fold in the walnuts and oats. Transfer to the skillet, smooth the top, and bake until puffed and the center looks set, 30 to 32 minutes. Let cool slightly before serving.

Cook the spiced apples

• In a medium saucepan over medium heat, combine the apples, butter, and 1/2 cup water. cover and cook, stirring occasionally, until the apples are just tender, 4 to 6 minutes. Remove the lid and reduce the heat to low. Add the sugar, raisins, cinnamon, and salt. cook, stirring occasionally, until the sugar dissolves and the juices have thickened slightly, about 2 minutes. Stir in the lemon juice to taste.
• Serve the cookie with the apples, topped with a drizzle of cream or a dollop of whipped cream.

Mini Skillet Cookies: Use mini (3-1/2 inch) cast-iron skillets for making individual servings. Divide the batter among 8 pans, and bake on a rimmed baking sheet for easy handling. They’ll be done about 10 minutes sooner than an 8-inch cookie.