Heat the butter in a small saucepan over medium heat. Once melted, add the flour and reduce the heat slightly. Stir until combined, then reduce the heat to low and cook until the mixture reaches a dark chocolate color (about 15 minutes).

Add the curry powder to the roux and stir to combine. Then add the garam masala and, optionally, cayenne. Stir and cook for 20 to 30 seconds, then transfer to a bowl and set aside.

Preheat a large pot over medium heat. Add the olive oil, onion, potatoes, squash, and carrot to the pot. Toss the vegetables to coat them with oil, then add the grated ginger and mix. Cover with a lid and reduce the heat to low so the vegetables can steam for 15-20 minutes, until mostly cooked. Periodically shake the pot or remove the lid and stir to keep the vegetables from burning.

Heat a large frying pan over medium heat. Add the olive oil and eggplant. Fry until browned (8-10 minutes) and then transfer them to a plate.

Wipe the pan clean and add the last tablespoon of oil. Then add bell pepper and asparagus and saute until slightly tender. Season with salt and pepper, then transfer them to the plate with the eggplant.

Wipe the pan clean and add the last tablespoon of oil. Then add bell pepper and asparagus and saute until slightly tender. Season with salt and pepper, then transfer them to the plate with the eggplant.

Once the hard vegetables are about 80% done, add the vegetable broth and bay leaf. Bring to a boil over medium-high heat, then skim any scum and cook until the vegetables are done all the way through. Turn off the heat and add the sauteed vegetables (reserving some to put on top when serving later) and mushrooms to the pot.