How to Make It
Tie together parsley sprigs, thyme sprigs, and bay leaves with kitchen twine to create a bouquet garni; set aside. Heat oil in a large saucepan over medium. Add onions and 1 teaspoon salt; cook, stirring occasionally, until onions are softened but not browned, about 10 minutes. Add garlic; cook, stirring constantly, until garlic is slightly softened, about 1 minute. Add 10 cups water, lentils, and bouquet garni. Bring to a boil over high. Reduce heat to low, and simmer, uncovered, stirring occasionally, until lentils are very tender, about 45 minutes.
Cook bacon in a large skillet over medium-high, stirring often, until bacon is crisp, 5 to 7 minutes. Transfer bacon to a plate lined with paper towels to drain; reserve drippings in skillet. Add mushrooms, cabbage, butter, salt, and pepper to bacon drippings in skillet, and cook, stirring often, until mushrooms are lightly browned, 10 to 15 minutes. Stir in bacon.
Beat cream, coffee, and salt with an electric mixer on high speed until soft peaks form, about 2 minutes.
When lentils are tender, discard bouquet garni. Transfer half of lentil mixture to a blender. Add cream, butter, pepper, and remaining 2 1/2 teaspoons salt. Secure lid on blender, and remove center piece to allow steam to escape. Place a clean towel over opening, and process mixture until very smooth, about 1 minute. Pour mixture into a large bowl. Transfer remaining half of lentil mixture to blender, and process until very smooth. Add to mixture in bowl, and stir well until combined.
To serve, ladle soup into bowls. Top evenly with cabbage and mushrooms. Divide toasted brioche among bowls; add a dollop of coffee whipped cream to each. Drizzle with olive oil, and garnish with microgreens, if desired.