Start this recipe by preparing the tarts. Roll out the pastry and cut out 4 circles each 14cm in diameter. Place on a baking tray lined with non-stick paper and chill in the fridge. Heat the butter and oil in a pan and sauté the garlic and mushrooms together for a few minutes to soften. Season well with black pepper, stir in the chopped parsley and remove off the heat. Remove the pastry circles from the fridge and prick with a fork, leaving a 1cm border edge untouched. Crumble over the goats cheese and cover with the prepared mushrooms, putting any juices left in the pan aside for the gravy. Lightly brush the edges of the tarts with the beaten egg and bake in the oven at 200`c for 20 minutes or until golden brown. Meanwhile, make the caramelized onion gravy. Heat the butter in a saucepan and soften the sliced onions for 3 minutes. Add the red wine and cook down for 20 minutes to intensify the flavours. Next, add in any reserved mushroom juices, along with the hot water, beef gravy pot and season well with black pepper. Stir well and continue to cook for just 3-4 more minutes to obtain a delicious, rich gravy. Serve the hot mushroom and goats` cheese tarts drizzled with the red wine and caramelized onion gravy.