Scrub the mushrooms under running water without mixing the three varieties. Cut the shiitake and oyster mushrooms in thick slices and set them aside, along with the whole porcini mushrooms. 

Place the whole porcinis in a heat-proof bowl with 1/2 cup very hot water and turn them to coat them with the water. Let the porcinis stand for 20 minutes to absorb the water, tossing them again once or twice. Squeeze them over the bowl to remove as much water as possible, reserving the soaking liquid. Chop the mushrooms coarsely and set them aside. 

Place the oil and butter in a large saute pan over medium heat, and heat them until the butter melts. Add the chopped shallots and cook until soft. Raise the heat level to high and add the sliced shiitake mushrooms. Saute the shiitakes for 2 minutes. Add the chopped porcinis and the sliced oyster mushrooms and cook for 2 to 3 minutes more, stirring continuously. Add the white wine and the reserved mushroom-soaking water, and continue cooking, uncovered, until the mixture is barely moist. Finally, add the brandy, salt, pepper, parsley chervil and chives. Reduce the heat to very low and let the flavors infuse for about 5 minutes more. Set the sauteed mushrooms aside. 

Roux:

In a small saute pan over medium heat, add the oil and whisk in the flour. Stir constantly until a dark peanut brown color has developed. It will require about 30 minutes. 

The Sauce:

Drain the oysters in a strainer over a large bowl to collect the liquor. Measure 2 cups of the oyster liquor and set them aside. Reserve the oysters themselves for the final stage of the recipe preparation.

Place the butter in a medium saute pan over high heat. When it is melted, add the shallots and cook for 2 to 3 minutes, or until just soft. Add the wine and deglaze the pan. Then add the oyster liquor and bring the liquid to a simmer.

Whisk in the dark roux, and, continuing to whisk constantly, simmer the mixture until it reduces by 1/ 4 and is thick enough to coat a spoon. Stir in the demi-glace, salt, pepper, parsley, chervil and chives. Remove from heat and set aside.

Final Assembly:

Preheat the oven broiler.

In a small skillet over high heat, melt the butter. Add the shallots, garlic, and thyme, and cook for 2 to 3 minutes, or until slightly soft. Add the bread crumbs and stir well to be sure they are evenly coated. Season to taste with salt and pepper.

Reheat the sauteed mushroom mixture from the previous recipe over medium-­high heat and stir in the prepared sauce. Bring to a simmer, add the oysters and cook until their edges just begin to curl. Spoon some of the mushroom-and­-oyster mixture into the prepared tart-pastry shells, dividing the portions evenly among the pastry shells. Sprinkle the seasoned bread crumbs proportionately among the tarts. Broil until the crumbs are just brown and the sauce is bubbly.