It is not a pie in the traditional sense, i.e., the filling is not placed into a pastry crust. Instead, all of the ingredients are mixed together in a single bowl and poured into a greased pie pan. But it is served like a pie, and is light, almost meringue-y, and delicious. And can be consumed without guilt.
Start by chopping the apples and nuts.
Next, mix the sugar, salt, egg and baking powder together. Then add in the flour.
Recipe, which I followed exactly, is below. (It says 3/4 c. sugar.)