Lightly butter both sides of the bread and using a large biscuit cutter cut out a disc of bread and use it to line the muffin tray.
Meanwhile melt the butter and add a little oil to the butter (to prevent the butter from burning).
Add in the bacon and brown off lightly, followed after a few minutes by the onion, garlic and mushroom. Allow this mixture to cook off for a few minutes until the vegetable mixture is gently sweated off-but without too much colour.
At this stage mix in the small amount of plain flour. You are using the flour to dry up the vegetable and bacon mixture.
Pour in the cream and this will immediately thicken the mixture. Cook this very gently for 4-5 minutes or until the taste of the flour is completely removed from the mixture. Season if required with a little salt and pepper and then add in the chopped parsley.
If time allows, allow this mixture to cool slightly and then divide the mixture between the previously lined muffin tin.
Sprinkle the top of each tartlet with a little grated mozzarella cheese and bake for 12-15 minutes until the bread has toasted and the cheese melted.
