Preheat the oven to 350 degrees. Slice the bacon strips in half. Arrange the bacon strips in muffin tins so that two pieces of bacon are in each tin, lying flat in an "x." Bake the bacon for 30 minutes or until crisp.

Meanwhile, heat the olive oil in a large heavy skillet. Saute the mushrooms, stirring frequently, until they are soft and dark. Set aside.

Heat the polenta in a double boiler and sir in the butter and grated parmesan cheese. Add additional salt to taste; remember that the bacon will be salty.

To assemble: Set the bacon crosses on a platter. Top each bacon cross with a dollop of polenta and a spoonful of mushrooms. Serve immediately.