Preheat the oven to 425F. Make roasted garlic. Peel the outer layers off of the garlic and cut off the top, being careful not to chop off too much—you don't want the garlic cloves to separate. Place the garlic in a foil packet. Drizzle enough olive oil over the garlic to cover it and sprinkle with salt and pepper. Roast for about 30 minutes.
Take the vegan butter and miso butter out of the fridge to soften.
Peel the potatoes, rinse them under cold water, dice, and place them in a large pot with enough water to cover them. Add a tablespoon of salt and bring to a boil. Once boiling, reduce to a simmer until soft. About 20 minutes.
Drain the potatoes when done. When the roasted garlic is done, let sit until cool enough to handle. Then squeeze out the garlic cloves with your fingers. Combine the butter and miso paste in a small bowl to create miso butter. Add the garlic to the bowl, using a fork to mash it into the miso butter. Mix everything together.
Heat a small skillet over medium low heat and add the miso butter to melt. Then add the coconut milk and whisk the mixture together. Keep the heat low so the pan doesn't bubble.
Add the potatoes to a medium/large bowl and mash them with a potato masher or a fork. Add the coconut milk mixture. Mix everything together, then add the rosemary. Add black pepper to taste. And salt if needed.