Add water and bouillon to a medium-sized pot and heat it over high heat. Let this come to a boil and then whisk it together. Reduce the heat to low to keep it warm.
Heat a large saucepan to medium heat, then add the olive oil to it. Once the oil is hot, carefully add the sage leaves in a single layer. Let them toast for about 30 seconds until crispy and fragrant. Take them out and place them on a paper towel for garnish later.
Add the onions to the oil and sauté them just until they start to appear translucent (3 minutes). Add the rice, garlic, chopped sage, salt, and pepper. Stir continuously as it toasts for 1-2 minutes, at most.
Pour in the white wine and use it to deglaze the pan by scraping at any bits that might be stuck to the bottom. Lower the heat to medium-low and continue to stir until most of the liquid has been absorbed by the rice.
Add a ladle of warm broth to the pan. Stir continuously as the liquid is absorbed. Continue this process of adding ladles of broth one at a time and stirring regularly for 18 minutes. Keep the temperature at a simmer and only add broth when most of the liquid has been absorbed. Reserve 1/2 cup of broth just in case you need it at the end.
After 18 minutes, the rice should be al dente. Try not to overcook it to mush because we want there to be some bite to it. At this time, stir in the pumpkin purée. Stir as it cooks for 2 minutes and then take the pan completely off the heat.
Stir in the vegan butter, vegan parmesan, and nutmeg. Serve the pumpkin risotto garnished with dried cranberries, pepitas, vegan Parmesan, and toasted sage leaves (optional).