Preheat the oven to 350° and lightly oil five cups of a standard-size muffin tin.
Place the chickpeas, panko, celery, carrot, onion, garlic, tomato paste, balsamic vinegar, nutritional yeast, soy sauce, flaxseed, basil, oregano, thyme and black pepper into the bowl of a food processor.
Pulse until the ingredients are finely chopped and well mixed.
Divide the mixture among the oiled muffin cups, forming a dome at the top of each muffin.
Bake the muffins for 25 minutes.
While the muffins bake, stir all of the sauce ingredients together in a small bowl.
After 25 minutes of baking, remove the muffins from the oven and cover the tops with a few spoonfuls of sauce. Reserve any excess sauce for serving.
Return the muffins to the oven and bake for another 5 to 10 minutes, until the sauce is set and the muffins pull away from the sides of the tins slightly.
Remove the muffins from the oven and allow them to cool for about 10 minutes.
Gently run a knife along the edges of each muffin to loosen it from the tin before removing.
If you have any leftover sauce, heat it up for a few minutes and serve it with the muffins.