Heat 2 tablespoons olive oil in a large frying pan then add the onions, cook on a medium heat without colour until soft and translucent. Increase the heat and add the chopped mushrooms. Cook until all the water from the mushrooms has evaporated. Tip out onto a plate and then return the pan to the heat, add a little more oil. Now add the remaining sliced mushrooms, cook over a high heat until all the water has evaporated and the mushrooms are nicely browned. Now return the chopped mushroom mix to the pan and add the garlic and Aleppo pepper. Cook on medium for a couple of minutes. Now add the tomatoes and season with salt and pepper. Cook on medium for 5-8 minutes, the pan is shallow so the sauce will reduce quite quickly. Remove from the heat and add the pine kernels.

When the peppers are ready, spoon the mushroom filling into the peppers. Tear the mozzarella and place a little on each pepper. Return to the oven and bake for a further 10-15 minutes, or until the mozzarella is bubbling and golden brown.