Combine chili powder, garlic powder, unsweetened chocolate, cinnamon, cumin, salt, cayenne pepper, allspice, cloves, and bay leaf in a bowl, mixing well until seasoning blend is fully incorporated.
Start by warming olive oil in a Dutch oven over medium heat; sauté onions and green bell pepper until lightly browned, approximately 10 minutes. Pour in vegetable broth and lentils; let it simmer for 20 minutes. Stir in seasoning mix, tomato sauce, apple cider vinegar, and Worcestershire sauce; simmer for an additional hour, adding water as needed if chili thickens too much.
Fish out the bay leaf from the chili, then use an immersion blender to blend until it reaches your preferred consistency.