In a large pot, cover the potatoes in water and bring to a boil. Boil for approximately 20 minutes, or until they’re fork tender. Reserve one cup of the potato water, drain the water and put the potatoes back in the pot.
While the potatoes are cooking, heat the 1 tsp olive oil on medium-high heat in a small skillet. Sauté the garlic and rosemary for 2 to 3 minutes, or until the garlic begins to brown. Remove from heat.
Add the 1 tbsp vegan butter, 32 oz of vegetable broth, reserved potato water, 3 tsp nutritional yeast, salt and pepper, and the garlic and rosemary to the potatoes. Stir and bring to a boil. Reduce to simmer and cook for 10 minutes.
Puree the potatoes with an immersion blender, or transfer by small batches to a blender to puree.