Preheat the oven to 375 degrees. Heat the olive oil in a sauté pan over medium heat. Add the onion and cook for about 3 minutes, or until the onion has softened. Add the garlic and cook briefly. Add the mushrooms and pepper.

Raise heat to high and cook for 5-6 minutes or until the mushrooms are tender and all the liquid has evaporated. Add the cream cheese and stir it into the mushrooms until completely incorporated as a sauce. Pour in the stock and blend it in. Add the parsley and thyme. Reduce the heat and simmer for about 15 minutes or until the sauce has reduced by half and is thick. Remove the pan from the heat. Stir in the Parmesan cheese. Spoon the mixture into a 6-cup casserole dish.

Soak the matzo sheets in cold water for 2-3 minutes, or until softened. Carefully squeeze the pieces to extract the water without breaking them. Place over the mushrooms. Brush with the melted butter. Bake for about 25 minutes or until the crust is crispy.