1. Melt the butter in a large saute pan over medium heat, then add the garlic and leek. Cook for a few minutes until soft and fragrant. Add the carrot and mushrooms, stirring to incorporate and make sure everything is covered in butter. Add a splash of the vegetable stock, then cover the pan and let cook for about 5 minutes, until the carrots are beginning to soften.
2. Add the rice and Imperial Seasoning, and stir for a minute or so. Begin gradually pouring in a little of the broth at a time, waiting until each batch has been absorbed before adding in more.
3. When just about all the liquid has been absorbed, stir in the Parmesan cheese. Season to taste with salt and pepper. The final consistency should be thick but not stuck together, so add a little more water or broth if need be to loosen it up.
Peel free to experiment with various mushroom types, but cremini, button, porcini, and portobello mushrooms are a great place to start.