Stir both broths, bacon, carrots, fresh mushrooms, lentils and bay leaf into slow cooker.
Cook the onion, garlic, thyme, bacon, tomato sauce, Porcini mushrooms over the stove for about five minutes before adding them into the crock pot
Cover and cook on low until the soup is thickened and the lentils are tender, 9 to 11 hours. Or, cover and cook on high for 5 to 7 hours.
When the soup has about 30 minutes left to cook, remove the bacon and bay leaf, and add in the chopped Swiss chard (I used greens because my store was out of chard).
When the soup is done, season to taste with salt and pepper and drizzle in a bit more olive oil.
Serve and enjoy! I served ours with toasted French bread, but a healthier option would be to skip it or use whole wheat.