Cooking the thighs confit-style is a guaranteed way to avoid any dryness - just look at that succulent meat falling off the bone! Stick it into a grilled cheese and you are well on your way to trying the best Christmas sandwich ever.
Begin the day before, if you have time. Liberally salt the turkey thighs and then leave them covered in the fridge overnight.
The next day, preheat the oven to 130°C. Wash off the salt and pat the turkey dry. In a sturdy cast iron or ceramic casserole, heat the goose fat until it liquefies.
Pop the thighs in, cover and cook in the oven for 2 hours. Add the garlic and herbs, then place the casserole back in the oven for another hour or two, until the thighs are very soft and you can shred the meat with a fork.
Drain the thighs, shred them and discard the bones.
Make your sandwich - stick all the ingredients, including a hefty wodge of delicious confit turkey meat, between the pieces of bread.
In a cast iron skillet or heavy bottomed frying pan, heat the butter over a low heat. Add the sandwich - there should be only the smallest of sizzles, you don't want the outside to burn before the cheese has melted. Fry both sides until things are looking gooey and the bread is golden and crisp.
Eat it, and worry about your cholesterol further down the line.