Place the mushrooms into a food processor and pulse in two batches until finely minced. Avoid over-processing to prevent a paste-like texture. Alternatively, mince them finely with a knife. Set aside.

In a large, heavy-bottomed pot or Dutch oven, add the tomato paste to a dry pan over medium-high heat. Stir constantly with a wooden spoon until the paste darkens slightly and develops a rich, caramelized aroma—approximately 2–3 minutes.

Slowly pour in the water, scraping the bottom to deglaze the pot. Add the tomato sauce, onion, garlic, chili powder, cumin, cinnamon, allspice, cloves, cayenne, salt, Worcestershire sauce, lentils, and minced mushrooms. Stir well to combine into a thick mixture.

Bring the mixture to a gentle simmer over medium-high heat, stirring frequently. Reduce the heat to low and continue to cook uncovered for 1–1½ hours, or until the lentils are tender but not mushy. Stir often to prevent sticking. If the liquid reduces too quickly before the lentils are cooked, add additional water as needed.

Once the lentils have reached the desired tenderness, stir in the apple cider vinegar and unsweetened chocolate (if using). Allow the chili to rest for 10 minutes before tasting and adjusting seasoning with salt or spices as desired.

Use an immersion blender to pulse the mixture lightly, just enough to break up some of the lentils and create a thicker, cohesive consistency. Do not fully purée.

Serve the chili immediately over cooked spaghetti, hot dogs, or in a bowl. Garnish with shredded plant-based cheddar, minced onion, and oyster crackers as desired.