Warm Spinach Salad

What you need:
1 (16 oz) package bacon ( i dont think i used this much)
1 tablespoon butter
1 8oz package sliced baby bella mushrooms
1/4 cup red wine vinegar
1 tablespoon soy sauce
2 teaspoons finely packed brown sugar
1/2 teaspoon salt
1 (10 oz) bag fresh baby spinach
1 cup shaved parmesan cheese
1/4 cup thinly sliced red onion

What you need to do:
In a large skillet, cook bacon over medium heat until crispy. Crumble bacon and set aside reserving 1/4 cup bacon drippings. In the same skillet, combine 1 tablespoon reserved bacon drippings and butter over medium high heat. Cook mushrooms until browned and tender. Remove from skillet and set aside. Add remaining 3 tablespoons reserved bacon drippings to pan. Stir in vinegar, soy sauce, sugar and salt. Cook over medium heat, stirring constantly until mixture begins to boil. Remove from heat. In a large bowl, combine 1 bag spinach, parm cheese, red onion, cooked bacon, and cooked mushrooms. Toss gently. Serve with hot dressing. Serves 6.