Cook the bacon in a large pot over medium heat until crisp, about 5 minutes. Remove the bacon. If there's excess bacon grease, drain off all but 1 tablespoon. To the pot, add the sausage and onion. Brown all over, about 5 to 8 minutes. Add the celery, garlic, and a pinch of chili flakes, cook 2 minutes. Pour in the broth, 1 cup water, the pesto, sun-dried tomatoes, lemon juice, and season with salt and pepper. Bring to a boil over medium-high heat. Stir in the kale and cook 5 minutes, until wilted, stir in the tortellini. Cook 2-3 minutes, then add the cream and parmesan. Remove from the heat. Stir in the reserved bacon.Serve the soup topped with additional parmesan and fresh thyme, if desired.