Preheat oven to 325º
Trim crusts of bread, flatten each slice with a rolling pin. Cut each slice into fours.
Press into mini cupcake pans and spoon ½ tsp butter into each cup.
Bake until browned at 325º for 8 to 10 minutes.
Keep an eye on them because they can quickly burn
Sauté onions, add mushrooms. Cook for 10 to 15 minutes until moisture is gone. Remove from heat, add flour, stir in cream. Bring to boil, simmer for 2 minutes. Remove from heat. Add rest of ingredients, mix well. Cool
Take out of oven and fill each cup with filling. (May be frozen at this point for later use).
Bake at 350º for 10 minutes. If frozen, 15 minutes.