Preheat the oven to 375F (190C). Line a 12-cavity muffin pan with paper liners.
Peel and core the apples, and cut them into small pieces.
Transfer the apple pieces to a medium bowl and toss with one tablespoon of flour. Set aside until ready to use.
In a medium bowl whisk together flour with baking powder, cinnamon and salt.
Add eggs with sugar and vanilla extract in a large bowl and mix to combine.
Gradually incorporate the oil.
Incorporate the flour mixture alternating with the buttermilk.
Don’t overmix the batter.
Gently fold the apples into the batter.
Divide the batter equally into muffin cups.