01 -
Season chicken with salt and pepper. Cook in olive oil about 6-7 minutes each side until done. Let it rest, then slice it thin.
02 -
Slice your avocado, onion, and tomato. Get your cheese slices ready.
03 -
Spread mayo and mustard on all bread slices.
04 -
Layer chicken, avocado, cheese, onion, and tomato on bread. Top with second slice, mayo side down.
05 -
Heat up butter in a pan. Grill sandwiches until golden and cheese melts, about 4 minutes each side. Press gently with spatula.
06 -
Let cool a minute, then cut in half and eat while warm.