Preheat oven to 350°F. Add the cinnamon apple ingredients to a small bowl and toss to combine. Set aside.
In a separate bowl, whisk together the flour, protein powder, baking powder, cinnamon and salt.
Add the eggs, milk, brown sugar, greek yogurt, butter and vanilla to a medium bowl and whisk well until combined. Add the dry ingredients to the wet ingredients and stir only until combined and there are no flour streaks. Make sure not to over mix this.
Fold in the apples. Grease a 10x15 inch sheet pan very well (also called jelly roll pan, you can use a 9x13 inch pan if you don't have one and bake a touch longer). Pour the apple cinnamon pancake batter and spread evenly on the pan.
Bake in preheated oven for about 14-18 minutes, or until the edges are golden, the center is set and a toothpick comes out of the center clean.
Cool for about 5 minutes before slicing and serving. Refrigerate or freezer leftovers (see notes for more details.)