Preheat your smoker to 275F and place your 12-inch cast-iron skillet directly on the grates.
In a medium saucepan, heat the sugar, salt, lemon zest, and juice over medium heat. Stir until the sugar dissolves completely (about 1-2 minutes). Pour the hot sugar mixture over your sliced peaches in a large bowl and give it a good stir to coat.
Melt the butter in the preheated cast iron skillet. Close the smoker lid and let the butter do its thing.
Combine the flour, sugar, baking powder, salt, cinnamon, and nutmeg in a bowl. Slowly stir in the milk until the batter is just combined. It's okay to have some lumps in there.
Pour the batter over the melted butter in the skillet. Carefully spoon the sugared peaches (and any juice in the bowl) over the top of the cobbler batter. Close the lid and smoke for about 60-70 minutes. You'll know it's done when the edges are browned and the cobbler dough has swapped places with the peaches and is mostly on top.
Remove the cobbler when it's ready and let it cool a bit before you dig in. I love serving it with a big scoop of vanilla ice cream.