Moussaka rolls

Ingredients (4 servings): 1 large (800g) eggplant, cut lengthways into 5mm-thick slices Olive oil cooking spray 2 teaspoons lemon juice 350g fresh ricotta cheese 1 green onion, thinly sliced 1 garlic clove, crushed ¼ cup parsley leaves, chopped 1 teaspoon fresh oregano leaves, chopped ¼ teaspoon ground nutmeg 1½ cups tomato passata (see passata recipe) ¾…