Place the potatoes in a large pot, add water to cover by at least 1-inch, season with salt. Bring to a boil over medium high heat, once boiling reduce heat to medium. Let the potatoes cook for 12-15 minutes or until the potatoes are tender.

Meanwhile, in a small pot melt the butter over medium high heat, and then let it cook and bubble until it starts to foam and smell like toasted nuts and caramel, about 5 minutes. Remove the pot from the heat. Set aside.

In a small non-stick pan, add ¼ cup oil over medium-high heat, once hot add sage leaves, cooking for 15 seconds each side, until they have curled and crisped but have not browned. Transfer to a paper towel lined plate. Set aside.

Once the potatoes are tender, strain and add back to the pot. Mash potatoes, adding buttermilk, milk, and brown butter, reserving 2 tbsp of butter, season with salt to taste.

Transfer to a serving bowl and drizzle over remaining brown butter. Garnish with fried sage leaves and pepper.