COOK IT.
Preheat oven to 350°F (177°C) and bake the potatoes directly on the oven rack until tender, about 1 – 1 1/4 hours. Cool 15 minutes.
Laying the potatoes on their sides, cut off the top 4 and reserve, and gently scoop out the flesh with a spoon, leaving 1/4-in (1cm) thick shells.
Force the scooped flesh through a ricer, or mash with a masher in a mixing bowl. Add the remaining ingredients, and gently mix with a fork or a wooden spoon. Taste to adjust the seasonings.
Spoon the filling back into the potato skins, and dot with butter. Replace the cut–off tops and gently wrap with aluminium foil in a way that signals the right–side up. Place on upper rack of a preheated barbecue and bake until heated through and beginning to brown, about 30 minutes.
If made ahead and refrigerated, bake for 35–40 minutes.
To Serve: Open foil, discard tops and garnish with a little extra grated cheddar and crumbled bacon.