Preheat oven to 400°F. Get cast iron skillet (oven proof) out on your stove top. In a large bowl, mix together flour, flax, sugar, baking powder, cinnamon, and salt. Cut in the butter until the size of peas. Pour in the 2/3 c. milk all at once, stir with a fork just until mixed. Knead once or twice, but don't over mix it. Melt the ¼ c. butter in the skillet over high heat. Add brown sugar and apples. Cook for 3-4 minutes, until apples begin to soften. Turn off the heat and drop the biscuit dough on top of the apples by large spoonfuls, so that there are individual biscuits covering all the apples. Bake at 400°F for 12 minutes. While it's in the oven, mix the powdered sugar and enough orange juice to make a glaze. When the biscuits are done, drizzle the glaze over top and enjoy.