Peel and cores apples and dice them into small pieces. Set aside.
Preheat the oven to 350° and line an 8 1/2 x 4 1/2 inch bread baking dish with parchment paper. Or, you can grease the bread dish with butter or oil spray all over the bottom and up the sides if you do not wish to use parchment paper.(Note: you can use a bread baking dish that is 9x5 if needed, you will just need to start checking if the bread is done 5-10 minutes earlier.)
Beat eggs and white granulated sugar in a bowl of an electric mixer for a couple of minutes, until light and fluffed.
Lower the speed to medium and add melted butter and vanilla extract until mixed in.
Lower the speed to "stir" and mix in flour, baking powder, and salt just until incorporated.
Still on low speed, pour in buttermilk and let in mix just until incorporated. Turn off the mixer.
Scrape sides and bottom of the bowl with a butter spatula and fold in diced apples.
Spread about a 1/3 of the batter in the prepared pan, sprinkle some of the cinnamon sugar mixture over the top. Spread another 1/3 and sprinkle cinnamon over the top. Repeat one last time.
Make sure the batter is spread evenly throughout the baking dish and bake for 55-60 minutes, until done. You can do a toothpick test of take internal temperature. Internal temperature of quick bread should be 200° when done.
*The amount of optional mix-ins are for individual use, if you want to combine nuts and raising or nuts and caramels, use smaller amounts of each. Nutritional information does not include optional mix-ins.