Core the apples and cut them into 1/2-inch wedges, leaving the peels on for structure.
Melt the butter in a 12-inch skillet over medium heat until it smells nutty and shows amber flecks, 2 to 3 minutes.
Add the apples and cook, turning every few minutes, until their cut faces begin to brown, about 6 minutes.
Stir in the brown sugar, cinnamon, nutmeg and salt until the sugar melts around the slices.
Add the lemon juice and cider, cover and cook until a knife meets a little resistance at the center of a slice, 3 to 5 minutes.
Uncover and toss for 1 minute until the sauce looks glossy rather than watery, then serve warm.