Peel and cut the potatoes into quarters.
Fill a large pot or bowl with cold salted water (be generous with the salt!) and let the potatoes soak for 15 minutes.
While the potatoes soak, prep the blueberry glaze. Mince the garlic, shallots and rosemary and set aside.
Season a sauce pan with olive oil on medium heat. You don't want the oil too hot, or the garlic will burn! After 1-2 minutes, put the garlic and shallots into the hot pan and sauté until fragrant.
Add the rosemary and continue to mix on medium heat for another 1-2 minutes.
Turn the heat up to medium high and pour the blueberries into the pot. Stir periodically and mash the blueberries as they become soft. After the blueberries begin to soften (2-3 minutes) add the red wine vinegar. Continue cooking for 10-12 minutes until the blueberries reduce and the consistency thickens.
Once the consistency seems more "gel like," reduce the heat to a simmer (the lowest heat possible) and place the lid on top. If it seems to be drying out a bit, add a tablespoon of butter to bring it back to life.
Rinse the potato slices once more in cold water. Then, pour water into a large stock pot and bring it to a boil. Place the potatoes inside the boiling water and let them cook for 15 minutes, until the potatoes are soft.
Drain the potatoes thoroughly. Place the goat cheese and butter into a large bowl.
Pour milk into a sauce pan and warm on the stove top on medium heat.
Put the potatoes into the bowl with the goat cheese and butter, and mash them into the cheese and butter with your preferred method. I use a potato ricer, as it helps the potatoes maintain maximum fluffiness! You can use a fork, or a potato masher. Mash them with your preferred method. I use a potato ricer, as it helps the potatoes maintain maximum fluffiness! You can use a fork, or a potato masher.
Slowly incorporate the warm milk into the mashed potatoes, until desired consistency is reached. Put foil on top of the bowl and set them aside.
Remove the blueberry glaze from the heat and let it sit.