Preheat your oven to 350 degrees
Fill a medium size bowl halfway with water. As you peel and slice your apples, you can put the slices in here, it will keep them from getting brown.
In another bowl mix or sift together the flour, baking powder, salt and sugar.
In a separate bowl whisk the eggs with the tangerine/orange juice and oil. Just a light whisk, don't get crazy.
Add the wet ingredients to the flour mixture and stir until things are just incorporated. It will be a thick mixture. Set aside while you finish the apples.
Strain your apples, discarding the water. Coat well with melted butter, then sugar, then cinnamon.
Prepare either a 9 x 11 pan or muffin pan with butter/flour or non stick spray. You want to begin layering with a think coating of batter, then apple, then batter.. etc. The batter will not pour so you just need to spoon it on.
Bake according to what you made. A 9 x 11 cake will need to bake for at least an hour, possibly a bit more. About 35 minutes into baking, loosely place a piece of foil on top to keep from browning too much. Muffins will take approximately 25 minutes to cook.
Let cool completely, sprinkle with powdered sugar to serve.