Preheat the oven to 200 degrees C. Place the potatoes in the preheated oven and bake for 45 minutes or until tender. Turn once or twice. Cool, peel and cut into 5mm slices.
Reduce the oven temperature to 180 degrees C.
In a medium bowl, stir together the spinach, spring onion, ricotta cheese, lemon juice, salt and pepper. Wet the matzo sheets under warm running water briefly on each side, just until pliable. Place one in the bottom of a square baking dish. Spread 1/4 of the ricotta mixture over it, followed by a layer of potato slices. Sprinkle 1/4 of the mozzarella cheese over the potatoes. Repeat the layers then finish with mozzarella cheese on top.
Bake for 35 minutes in the preheated oven, until the cheese on top is bubbly and golden brown. Keep warm until you are ready to serve. Cut into squares.
Feel free to dress it up with the seasonings you are most keen on.