Prepare the oven and dish. Preheat your oven to 350°F and spray a 9x13 casserole dish with nonstick baking spray.

Make the filling. In a large mixing bowl, use an electric hand mixer (or a stand mixer if you prefer) to mix the brown sugar, eggs, condensed milk, half a cup of pecan halves, half a cup of chopped pecans, half a cup of butter, vanilla, and salt until smooth and combined well.

Mix the topping. In a separate large bowl, add the cake mix, cinnamon, vanilla, maple syrup, and nutmeg, along with the remaining half cup of butter. Use a fork or clean hands to work the butter into the dry mixture until it’s thoroughly combined and it resembles small crumbles.

Add the filling to the dish. Pour the wet mixture into the bottom of your prepared casserole dish and then sprinkle the dry mixture over the top until the filling is completely covered.

Bake. Top with the remaining pecans and bake uncovered for 45 minutes or until the center is set and no longer jiggly.

Cool slightly before you garnish and serve. Allow it to cool slightly before drizzling with caramel sauce and serving warm or at room temperature with ice cream!