Preheat your oven to 350°F (175°C). Prepare a 9×13-inch baking dish by lining it with foil and spraying both the dish and the foil with non-stick spray. This makes it much easier to remove the bars after baking and helps with cleanup. I always use this method for bar recipes!

In a large bowl, use a hand mixer to cream together the unsalted butter, granulated sugar, and vanilla extract until the mixture is light and fluffy. Then, add in the eggs, one at a time, mixing well after each addition. Over the same bowl, sift in the all-purpose flour and baking powder. Continue mixing until just combined into a smooth batter.

Pour about three-quarters of the batter into the prepared baking dish and press it out evenly to form the bottom layer. Next, spread the apple pie filling evenly across the batter layer. Sprinkle the ground allspice and crushed pecans over the apple filling for added flavor and texture.

Spoon the remaining batter from Step 2 in dollops over the apple pie filling, spacing them out to create a rustic, uneven topping. Bake the assembled bars in the preheated oven for 30-40 minutes, or until the top is golden brown. Once baked, transfer the baking dish to a wire rack and let it cool while you prepare the glaze.

In a small bowl, whisk together the powdered sugar and heavy cream until smooth. If you'd like a thinner glaze, add an extra tablespoon or two of cream until you reach your desired consistency. Drizzle the glaze over the cooled apple bars before serving. To make the glaze extra delicious, I sometimes add a tiny splash of vanilla extract or even a pinch of cinnamon.