Preheat oven to 400°F (200°C). Scrub and pierce potatoes with a fork. Rub with avocado oil, season with salt and pepper, and bake on the rack for 50–60 minutes until skins are crisp and flesh is tender. Cool slightly.
Halve potatoes lengthwise, scoop out most flesh, and mash with butter, hot milk, salt, and pepper until fluffy.
Return mash to shells, make a well, add beef bacon, cheddar, and crack in an egg. Season lightly.
Lower oven to 350°F (190°C) and bake 15–20 minutes until whites are set and yolks soft.
Rest briefly, then serve warm with melted cheese, crisp bacon, and runny yolks.