Butter one side of each baguette slice.
Place butter-side-down in skillet on medium-low heat.
Layer on top one slice of cheese, two half slices of bacon, avocado, and another piece of cheese.
Top with another slice of bread, butter-side-up.
Cook until bread is golden and cheese is melting.
Flip over and cook other side.
Transfer to an oven-safe baking dish and reheat in the oven before serving.