Heat 2 cups water until hot - about 2 minutes in the microwave should do. Add dried porcini mushrooms to water and set a small bowl on top of the mushrooms to keep them submerged; let stand until they are soft, about 20 minutes. Remove mushrooms from liquid and set aside.
In a medium sauce pan, combine vegetable broth and 4 cups water and bring to a simmer.
Meanwhile, melt butter in a large pot over medium heat. Add onion and cook, stirring occasionally, until softened, about 5 minutes. Add garlic and thyme and cook until fragrant, about 30 seconds.
Add porcini mushrooms and cook for 2 minutes.
Add Carnaroli rice; cook, stirring constantly, for 1 minute. Then add wine and simmer until evaporated, about 1 minute.
Add ½ cup hot broth mixture; simmer, stirring occasionally, until almost absorbed. Continue adding ½ cup hot broth mixture in this manner until rice is tender and mixture is creamy, about 30 minutes.
Turn off heat and stir in Pecorino Romano cheese. Season with salt and pepper to taste.
Garnish with parsley, if desired, and serve immediately.
Recipe by Two of a Kind at http://www.twoofakindcooks.com/risotto-ai-funghi-porcini/