In a saucepan, combine the cream, milk, butter, rosemary, garlic, sage, and thyme. Bring just to a boil (bubbles forming around the edges), then remove from the heat and let steep about 20 minutes.
Put the peeled russet potatoes in cold water, bring to a boil, and add salt. Cook until fork-tender.
Strain the potatoes and let them air-dry for a couple of minutes, then return to the pot over the lowest heat.
Pass the potatoes through a ricer (or mash), then slowly work in the strained infused cream mixture a little at a time until creamy and smooth.
Spread into an oven-safe serving dish and gently brush the top with melted butter.
Broil about 10 minutes, until the top is golden. Serve (they are good enough to stand alone, no gravy needed).
Method transcribed from the video (rough); amounts to taste. Justin Chapple's brown butter mashed potatoes, shared by Corre Larkin on Instagram.
