Preheat oven to 350°F (175°C). Grease or line a loaf pan with parchment paper.
Heat olive oil in a skillet over medium heat. Sauté onion, celery, and carrot for 5–7 minutes until softened.
Add mushrooms to the skillet and cook for 3–5 minutes until they soften. Remove from heat and let cool slightly.
In a large bowl, mash chickpeas until mostly smooth.
Mix in sautéed vegetables, bread crumbs, parsley, tamari, Worcestershire sauce, ketchup, barbecue sauce, smoked paprika, salt, and pepper.
Press the mixture firmly into the prepared loaf pan, smoothing the top.
Bake for 45–50 minutes until the top is browned and edges pull away from the pan. Cool for 10 minutes before slicing. Garnish with parsley if desired.