Preheat oven to 175 degrees C. Line a deep 22cm springform pan with aluminum foil and coat generously with cooking spray.
Make the brownie
Whisk brownie mix, oil, 2 eggs and water together in a bowl until well combined. Spread batter into the prepared pan.
Bake in the preheated oven until a toothpick inserted into the centre comes out clean, about 30 minutes. Remove from oven and leave oven on.
Make the pecan pie layer
Whisk brown sugar, corn syrup, 2 eggs, bourbon, vanilla extract and salt together in a bowl. Add melted butter slowly, whisking until well combined. Add pecans and stir to coat in the filling. Pour gently over the brownie layer; spread evenly using a spatula.
Bake in the oven until centre is set, 30 to 35 minutes. Let cool to room temperature, at least 2 hours.
Honey can be used in place of the corn syrup.
The directions for making brownies are based on the particular brand mentioned. Follow instructions on the box if using a different brand.