Heat a large pot or dutch oven over medium-high heat.
Add olive oil and chili flakes for 30 seconds before adding onion, carrot and celery. Coat veggies, season with salt and pepper and cover pot with a lid. Cook, stirring often for 5-7 minutes.
Add garlic and mushrooms. Toss to coat. Let the mushrooms cook down stirring periodically. Once mushrooms start to soften, stir in lentils and fresh thyme. Season with salt and pepper.
Add stock, water and parmigiano rind. Bring to a boil, then reduce to medium-low, partially covered to cook until lentils are cooked. Approximately 20 minutes.
Once lentils are done, add spinach. Spinach will wilt rather quickly. Taste for seasoning and serve into bowls.
Garnish with grated parmigiano, pinch of chili flakes and a drizzle of olive oil.
Special Notes: Find my favourite Dutch oven and chefs knife below!