Heat oven to 350 F and grease 12 standard-sized muffin cups or line them with parchment paper.
In skillet over medium, heat oil. Add onion and salt; heat until onion has softened; about 5 minutes. Add mushrooms to pan and heat until softened, about 3 minutes.
To food processor container, add walnuts and pulse a few times into fine pebbles. Add mushroom mixture, sweet potato, chipotle peppers, and thyme, and pulse to combine. Lastly, add lentils, oats, tomato paste, soy sauce, and cumin; pulse to loosely combine—but not to puréed. Divide among muffin cups and bake for 30 minutes. Spread barbecue sauce over tops and bake for another 10 minutes. Remove from oven and let rest for 10 minutes in pan. Then gently remove and serve.
Notes
Per serving : 327 calories; 13 g protein; 14 g total fat (1 g sat. fat); 40 g total carbohydrates (5 g sugars, 10 g fiber); 536 mg sodium