Preheat the oven to 350 degrees Fahrenheit with a rack in the middle position.
Spray a Bundt pan thoroughly with baking spray.
In a small sauce pan set over medium heat, heat the butter and water together until boiling. As soon as the mixture boils, take if off the heat.
In the meantime, combine the flour, salt, brown sugar, granulated sugar, baking soda, cinnamon, nutmeg, and diced apples in a large mixing bowl. Mix together thoroughly with a rubber spatula.
When the water and butter mixture has cooled slightly, add it to the mixing bowl with the dry ingredients. Mix a few times.
Add both of the eggs. Mix until combined.
Add the vanilla extract and the sour cream. Mix until combined.
Pour into the prepared Bundt pan, place the Bundt pan on a baking sheet just in case of spill over, and bake for 45 to 55 minutes. The cake is done when a cake tester comes out clean. Mine take 50 minutes, but this varies depending on your oven.
Let the cake cool in the pan for 10-15 minutes, then invert onto a cooling rack to cool completely.
Slice and serve with whipped cream or vanilla ice cream.
