In a large bowl mix dry ingredients: flour, baking powder and salt together and set aside.
In a separate bowl, whisk wet ingredients: oil, orange juice, sugar, vanilla and eggs. Mix wet ingredients into dry ones very well. The resulting batter is very thick and will seem like there is not very much of it - that's OK.
Grease a 7” cake pan and pour half of batter in.
Spread half of apples on top of the batter.
Add the remaining batter covering most of the apple pieces.
Finally, spread the remaining half of apples and any juices on top.
Cover the cake pan tightly with aluminum foil.