Preheat the oven to 350. Grease a donut pan or muffin tin with avocado oil and set aside.
In a small sauce pan, bring the apple cider to a boil and cook until the cider is reduced to 1/2 cup. This may take 20-30 minutes. Set aside and allow to cool slightly while you finish the other steps.
In another small pan over medium heat, add the butter and melt; add the diced apples and pinch of salt and cook until the apple soften, about 6 minutes. Set aside.
In a medium bowl, add the flour, baking powder, salt and cinnamon and stir to combine. Add the apples and toss to coat.
In another bowl, beat the honey and butter until light and fluffy. Add the egg, vanilla, and cider. It's okay if this mixture looks clumpy. Add to the flour and apple mixture and use a spoon or hand mixer to blend just until no flour remains. Do not over beat.
Transfer to a zip lock bag or piping bag and trim the end. Squeeze the batter in to the pan until 3/4 full. Bake until a toothpick inserted comes out clean--12-15 minutes or so depending on your oven. Turn out on a wire rack to cool for 5 minutes.
Melt remaining butter and set aside. Blend sugar and cinnamon in a small bowl. Brush donuts with butter and dip the tops in the cinnamon sugar. Serve warm or store in an air tight container for up to three days.