Preheat oven to 350 degrees F. Spray muffin pans (regular size or mini) with cooking spray. I like to use coconut oil spray.

Place the butter in a large bowl and melt it in the microwave. You could also melt the butter in a pot on the stove.

Add the honey or pure maple syrup, applesauce, plain Greek yogurt, milk, eggs and vanilla to the bowl with the butter. Whisk until well combined.

Add the baking soda, baking powder, salt and cinnamon to the bowl with the wet ingredients. Whisk until well combined.

Add the white whole wheat flour. Use a rubber spatula to mix it in until almost combined.

Add the chopped apple, reserving a few apple pieces for the tops of the muffins, if desired. Use the rubber spatula to mix in the apple until just combined.

Scoop the batter into the greased muffin pans, filling each well about 2/3 full. If you reserved some of the apple pieces, press them into the tops of the muffins.

Bake regular size muffins for 16-18 minutes, until a tester inserted into the center comes out clean. Bake mini muffins for about 12 minutes.

Let cool in the pan for 10 minutes, then transfer to a wire rack to finish cooling.

Store muffins in the refrigerator for up to 3 days or in the freezer for up to 3 months.