Add the sliced mushrooms, diced onion, and minced garlic directly to the slow cooker insert.
In a small bowl, whisk the vegetable broth and flour together until smooth. Pour the mixture over the mushrooms and stir once.
Stir in the vegan Worcestershire sauce, smoked paprika, and thyme until everything is evenly combined.
Cover and cook on low until the mushrooms are very tender and the sauce has thickened.
While the sauce finishes, cook the wide egg-free noodles in a large pot of salted water according to the package directions. Drain and set aside.
Stir the coconut milk into the slow cooker. Taste and adjust with salt and black pepper.
Divide the noodles among bowls and spoon the mushroom sauce on top. Finish each serving with a sprinkle of chopped parsley.