Add the avocado oil to a large non-stick skillet and heat to medium-high. Add the chopped onions and sprinkle liberally with sea salt. Cover the skillet and cook, stirring occasionally, until the onions leach a lot of their liquid, turn translucent and have softened.
Remove the cover from the skillet and reduce the heat to medium or medium-low. Continue cooking, stirring occasionally, until the onions are brown and caramelized, about 50 to 60 minutes total.
Cut the top off of the bulb of garlic and place it on a sheet of foil. Drizzle with avocado oil then wrap the bulb in the foil so that it’s fully covered. Roast at 400 degrees Fahrenheit for 35 to 45 minutes, or until the garlic cloves are deeply golden-brown. Remove garlic from the oven and set aside until ready to use.
Once the garlic is cool enough to handle, turn the bulb upside down over a cutting board and squeeze it to release all of the cloves. The cloves should squeeze out relatively easily. Chop up the cloves into finer pieces.
Bring a pot of water to a boil on the stove top. Peel and chop the potatoes into 3-inch chunks (or roughly equal sized chunks) and transfer to the boiling water. Cook at a continuous boil until the potatoes are very soft when poked with a fork, about 15 to 20 minutes. Drain the potatoes into a colander, then transfer them back into the same pot you used for boiling.
Add the buttermilk, parmesan cheese, butter, and sea salt to the pot with the hot cooked potatoes and mash using a potato masher until the potatoes reach your desired consistency. Taste the mashed potatoes for flavor and add more sea salt, parmesan cheese, and/or butter to taste.
Add the caramelized onions and chopped roasted garlic to the pot and stir well to combine.
Serve with your main dish and enjoy!
