Preheat oven 176 c | 350 f. Lightly grease a 9-inch skillet (or round pie dish) with butter/oil; wipe over excess with paper towel and set aside.: The air should warm evenly before the pan goes in, creating a predictable bake and a nicely browned edge. You will notice the oven smell change from neutral to warm and slightly sweet as it reaches temperature, which helps the cookie rise and set correctly. Greasing the skillet ensures the cookie releases easily later, and wiping excess prevents an oily bottom. A common mistake is skipping the wipe step, which can pool butter and cause uneven browning around the base.
Combine all Apple Pie Filling ingredients in a small saucepan. Bring to a boil; reduce heat and gently simmer while occasionally stirring, until apples have softened (about 10 minutes) and caramel has thickened.: As the filling simmers, you`ll see the apples soften and the sugars melt into a glossy caramel that clings to the fruit. Listen for a soft bubbling and smell the cinnamon lift as it cooks, which signals that flavors are melding. Stirring occasionally prevents the sugar from sticking and burning, and simmering gently preserves apple texture without turning them to mush. Avoid vigorous boiling, which can evaporate too much liquid and make the filling overly sticky rather than saucy.
In the meantime, prepare cookie by combining the butter, sugar and vanilla into a large bowl, and whisk until light and creamy. Add the egg and whisk again until smooth.: Creaming until light introduces air that makes the cookie tender. You`ll notice the mixture lighten in color and become smoother, with a faint, sweet aroma of vanilla . The texture should be free of grainy sugar pockets; if it still feels granular, whisk a bit longer. Over mixing with high speed can make the dough too soft, so aim for a gentle, fluffy texture rather than an overly aerated batter.
In another bowl, mix together the flour, baking powder and salt. Using a wooden spoon, stir flour into the batter and slowly mix until just combined (do not over beat). Spoon 2/3 the cookie dough into the pan.: Incorporating the egg binds the batter and adds moisture. The batter will look more cohesive and slightly glossy after mixing the egg in. If the batter splits or looks curdled, a brief, gentle whisk usually brings it back together; do not panic and add more liquid. A frequent error is adding a cold egg to very soft butter, which can cause separation, so use room temperature ingredients for a smooth mix.
Pour the Apple Pie Filling over the cookie dough 1-inch from the edges. Spoon remaining cookie dough batter over the top of the apple mixture and sprinkle with cinnamon sugar (optional): Dry ingredients should be evenly distributed so the rise and seasoning are uniform. You may notice a dry, powdery aroma with a faint mineral note from the salt . Sifting is optional, but whisking thoroughly eliminates clumps and ensures the baking powder is dispersed. Not mixing the dry ingredients well can create pockets of baking agent that affect texture, so take the extra moment to combine them evenly.
Bake for 35-40 minutes until a toothpick inserted into the centre comes out slightly dirty. The cookie will be moist and fudgy when taken out, but will set and firm as it cools. Don't over bake or it will become dry.: Folding flour gently preserves the batter`s tenderness. You`ll feel the batter thicken and see streaks disappear as the flour incorporates. A slightly sticky texture is normal, and it will bake into a moist center rather than a dense block. Over beating develops gluten and makes the cookie tough, so stop when the flour is mostly combined and a few tiny streaks remain, they will disappear during resting and baking.
Once cooled, cut into 16 slices. Serve with Salted Caramel Apple Topping.: The dough will spread into a rustic base, and pressing it lightly with the back of the spoon helps form an even layer. You want a slightly thicker rim so the edges can brown and crisp, creating contrast with the soft center. If the dough is too cold and stiff, it may be hard to spread, but a few seconds at room temperature softens it just enough. A common slip is to press so hard you compress air pockets that would have contributed to tenderness in the finished cookie.
Combine all ingredients into the same saucepan you used for the Apple Pie Filling. Bring to a boil; reduce heat and gently simmer until apple slices have softened and caramel has thickened.: Leaving space near the rim allows the cookie to bake up and brown, framing the filling. As you pour, you`ll see the glossy caramel and softened apples settle into the dough pocket, and the contrast is visually satisfying. This placement prevents the filling from leaking over the sides and burning. Overfilling or pushing the filling to the edges can cause the caramel to bubble over and scorch, so keep that one inch clear.
Spoon remaining cookie dough batter over the top of the apple mixture and sprinkle with cinnamon sugar (optional): Dabbing and dropping the remaining dough in patches creates a patchwork top that will bake into slightly crisp islands with tender valleys between. The cinnamon sugar melts and forms sweet, crunchy spots on the surface. Aim for even coverage rather than smearing the dough thin, which would reduce the pleasing contrast between top and bottom. A common error is flattening the top too much and losing the texture contrast.
Bake for 35 to 40 minutes until a toothpick inserted into the centre comes out slightly dirty: While baking, the kitchen will fill with buttery, spiced aromas and the edges will turn a deep golden brown. The center should jiggle slightly and feel soft but not liquid; the toothpick test showing moist crumbs indicates the perfect fudgy interior. The cookie continues to set as it cools, so pulling it a touch early preserves tenderness. Over baking results in dryness, so resist baking until completely clean on the toothpick.
Once cooled, cut into 16 slices. Serve with Salted Caramel Apple Topping: After resting, the dessert firms and slices neatly, revealing layers of caramelized filling and cookie. I love serving each wedge warm or at room temperature, and the topping adds a glossy, sweet finish. A misstep is slicing while too warm, which can cause sloppy wedges, so wait until the skillet is warm to the touch for cleaner portions.
Combine all ingredients into the same saucepan you used for the Apple Pie Filling. Bring to a boil; reduce heat and gently simmer until apple slices have softened and caramel has thickened: Making the topping in the same pan layers flavor and simplifies cleanup. You will see the apple slices soften quickly and the mixture bubble into a thick, shiny sauce that clings to the fruit. Stirring keeps the caramel from sticking and ensures even cooking. If you let it boil too hard, the sauce can reduce too far and become gluey, so keep it gentle and watch the consistency closely.