In a skillet heat the butter; add the onion and brown lightly. Add the mushrooms and cook about 3 minutes, stirring often. Add the thyme, salt and pepper and sprinkle with flour. Stir in the cream and cook gently until thickened. Mix cream cheese and butter thoroughly. Add flour and work with the fingers or pastry blender until smooth. Chill well, at least 30 minutes. Heat oven to 450 degrees. Roll out dough to 1/8-inch thickness on a lightly floured surface and cut into rounds with 3-inch cutter. Place a tsp. of Mushroom Filling on each and fold over the filling. Press the edges together with a fork. Prick tops to allow for the escape of steam. Place in ungreased baking sheet and bake until lightly browned, 15 minutes.