Add 1 tablespoon bacon drippings, 2 tablespoon Challenge Butter to a large sauce pan. Heat over medium high. Once bacon drippings and butter are melted add 2 ½ teaspoons flour. Cook for 1-2 minutes stirring constantly.
Whisk in 1 cups heavy cream. Continue whisking until all the flour mix is incorporated and there are no lumps. Add remaining ½ cup cream and blend well.
Reduce heat to low. Add 1 tablespoon Challenge Butter, remaining Mushroom Blend, reserved burger drippings, and chopped bacon. Stir to combine. Season with 1 teaspoon salt and fresh cracked pepper. Keep warm
Making the Patty Melt:
Butter 8 slices Marbled Jewish Rye bread with Challenge butter. Using a large sauté or grill pan turn heat to medium and place 4 slices bread, butter side down in the pan
Add 2 slices Swiss cheese to each piece of bread, lay two slices bacon on top of 2 of 2 cheese breads and a cooked burger patty on top of 2 of the pieces of bread.
Top both burgers with caramelized onions, 2 more slices bacon for each burger, and top with 1-2 tablespoon mushroom gravy.
Cover the burger with second slice of bread and cook for 2-3 minutes. Carefully, flip patty melt over and continue cooking until cheese is melted, about 3 more minutes or until heated through.