Pre-heat a large skillet over medium-high heat. Add the bacon and cook for 5 minutes until it has softened but is not fully cooked. Add the onion and sauté for a few minutes, until it starts to soften. Add the mushrooms and thyme, and continue to cook until the bacon is cooked through and the onions have browned. Season with salt and freshly ground black pepper. Remove the pan from the heat and let the mixture cool completely.
**Pinwheels can be made up to 2 months in advance. Freeze the log whole. Rest on the counter for 30 minutes, then slice and bake 20 to 23 minutes.