For buttermilk syrup: Melt butter in medium pot (should be a tall pot). Once butter has melted, add both sugars and water to the pot and stir until all sugar is well coated, then stir in buttermilk.
Bring the mixture to a boil and allow to boil for 3 to 4 minutes. Remove mixture from heat and add baking soda (be very careful as the mixture will bubble up). Once baking soda has been added, stir the mixture for 1 to 2 minutes until it begins to settle. Stir in vanilla and salt until fully incorporated. Pour syrup into a small carafe and set aside until ready to use.
For pancakes: Place flour, sugar, baking powder, baking soda, cinnamon, and salt into a mixing bowl and whisk together. Add buttermilk, eggs and butter and stir with fork until mixture has just come together and no dry pockets remain. Fold in apples until just combined.
Melt 2 tablespoons butter onto a griddle, in a cast iron pan or nonstick skillet over medium heat. Pour ⅓ cup batter onto the buttered pan and allow pancakes to cook for 3 to 4 minutes. Once you see the edges begin to cook and air bubbles popping on the surface, flip pancakes and cook for an additional 3 minutes.
Transfer finished pancakes onto a baking sheet (you can keep finished pancakes in a warm [200˚F] oven while the remaining pancakes cook) and repeat until all the batter has been used.
Serve pancakes with the brown sugar, buttermilk syrup and more butter, if desired.