Place the butter, brown sugar and salt in a medium saucepan over medium heat, and stir to combine until the butter is melted. Simmer without stirring for 2 minutes.
Add the heavy cream very slowly and carefully, stirring constantly (it will bubble and spatter). Simmer for 5-6 minutes, stirring occasionally. Remove from heat and set aside.
Apples
While the caramel syrup is simmering, melt the butter in a small skillet over medium heat. Stir in the brown sugar.
Add the apples to the skillet with the cinnamon and stir to combine.
Cook the apples, stirring occasionally, for 5-7 minutes until they are tender and lightly browned.
Pancakes
In a medium bowl, whisk together the flour, sugar, baking powder, baking soda, cinnamon, and salt.
In another medium bowl, whisk together the buttermilk, milk, eggs, melted butter, and vanilla.
Add the flour mixture to the buttermilk mixture and stir to combine (do not overmix). The mixture will be lumpy but do not worry about this.
Melt a teaspoon of butter in a large non-stick skillet or griddle over medium-low heat, and spread it around with a paper towel.
Add about ⅓ cup of batter to the pan (you should be able to fit two at a time in a 12 inch skillet). Cook the pancakes for 2 minutes until golden brown underneath, and flip with a spatula. Cook for one minute on the other side and remove to a plate. Continue with remaining batter.
Serve pancakes with apples and caramel syrup.
Notes
*Caramel Sauce and apples can be made ahead and refrigerated.