Preheat the oven to 350 degrees.
In a pan over medium heat, saute the sausage and grated potatoes in olive oil for approximately 6 minutes until lightly browned.
In a large mixing bowl, transfer cooked sausage and potatoes, then add in the milk, water, egg substitute, tahini, salt, and pepper. Stir. Then, stir in the dry pancake/waffle mix. Spray a 13 x 9 glass pan with non-stick spray and evenly distribute the batter.
In a separate bowl, lightly toss the apple slices with lemon, cinnamon, and coconut sugar. Then lay them on top of the batter in a fairly thin / even layer. You can press them down a bit into the batter.
Bake for 40-45 minutes until the casserole is set. Serve hot with maple syrup.