Preheat the oven to 375 F. degrees and prepare a 2 muffin tins with cupcake liners.
Whisk the flour, baking soda, ground cinnamon and salt in a bowl and set aside.
Using a hand held mixer or a stand mixer on medium cream the butter and sugar for 3 minutes.
Next beat the egg in until completely incorporated.
Add the applesauce and beat well. Combine the buttermilk and warm water.
Alternately add half the liquid and half the flour mixture to the bowl while beating on low.
Once all the ingredients have been added to the bowl beat on medium for 2 minutes.
Fold the apple pieces into the batter.
Evenly divide the batter between 24 muffin wells filling them ¾ full.
Bake for 18 minutes turning the pan half way through the baking time.
Remove the pan from the oven and allow to cool for 10 minutes. Remove the muffins from the pan to cool on a wire rack.
Frost with cream cheese frosting or my Caramel Apple Coffee Butter Cream Frosting recipe