1. Melt butter in a small cast iron skillet and once hot, add the onions and cook until softened. Add half the apple cider, cooking for another 3-5 minutes. Add the remaining apple cider and cook until onions are dark golden and caramelized. Mix in the thyme and prosciutto and cook prosciutto for about 2-3 minutes until firm – remove from heat.
2. In a large cast iron skillet, melt butter, and brush two slices of sour dough bread with either melted butter or olive oil. Sprinkle your seasoning on the oiled side of the bread, and on the dry side, layer your gruyere cheese, prosciutto or bacon, caramelized onions and Starr Ranch Growers apple slices. Place the second pieces of oiled bread on top to form a sandwich, with the oiled side facing upward. Add the sandwich to the buttered skillet, paying close attention and flipping after about 2 minutes on each side until nicely golden browned.
3. Top with additional seasoning and fresh thyme. Enjoy!