Over medium heat add the bacon, butter, and onion. Cook for 7 - 8 minutes, stirring occasionally, or until onions are very soft and taking on color. Stir in the garlic and cook for another 1 - 2 minutes.
Add the mushrooms and cook for another 6 - 7 minutes, stirring occasionally, until mushrooms soften and take on color.
Stir in the flour and thoroughly mix, 1 - 2 minutes. Stir in the tomato paste and thoroughly mix, 1 - 2 minutes. Whisk in the broth, thyme, salt and pepper. Gravy should thicken once all ingredients are thoroughly combined. Simmer for 5 - 10 minutes, or until desired consistency.
If adding the cream make that the final step and remove from heat. If not, serve immediately over potatoes or your favorite meat.