Dice the onion, carrots and celery.
Melt the butter in a large pot. Add the diced onion, carrots and celery, and sauté until the vegetables are tender and the onion is translucent, about 8-10 minutes.
Add the flour to make a roux. Stir until the vegetables are coated, and then add the vegetable broth and coconut milk.
Cover and let simmer for 20 minutes.
While the vegetables cook, rehydrate the tofu skins, if using. Place tofu skins in a bowl, add the baking powder and enough hot water to cover the skins. Let sit for 15 minutes, then drain. If using tofu instead, just dice up the tofu.
Bring the vegetable broth to a boil. Add the noodles one at a time to the boiling broth. Add the tofu skins.
Reduce heat, cover, and cook for at least 20 minutes, until the noodles are tender and chewy.
Check and stir the pot pie occasionally. If the noodles aren't completely covered by the broth, or the broth becomes too thick, add more water, broth or coconut milk.
Taste, then season well with salt and pepper.
Serve hot. This keeps for up to 3 days and reheats well.