Preheat the oven to 325°F. Heat a well-seasoned 10.25-inch cast iron skillet over medium-low heat. Add 1/2 cup of the butter, brown sugar, corn syrup, salt, and pecans. Stir frequently until the butter melts and the sugar dissolves. Remove from the heat and set aside.

Melt the remaining 1/2 cup of butter. In a large bowl, combine it with the cake mix, eggs, and water. Beat for about 2 minutes until fully combined. Pour the mixture evenly over the caramel sauce and pecans in the skillet. Bake for 45 to 50 minutes, or until the cake is set and a toothpick inserted into the center comes out clean. (If you're unsure about the skillet size, it may be a good idea to place the skillet on a rimmed baking sheet or pizza pan to catch any drips that might spill over in the oven.)

Allow the cake to cool for about 10 minutes. Then, place a large plate or platter over the skillet and carefully flip it to turn the cake out onto the plate. (A dish towel can help with this as the pan may still be hot.) Scoop any remaining pecans and sauce from the skillet over the cake. Serve warm.

*Note: If nutritional values are provided, they are estimates and will vary depending on the brands used. These values do not include optional ingredients or when ingredients are added to taste. For a more accurate calculation, use an online nutritional calculator with your favorite brands.