Slices of those delicate summer squash baked with cheesy goodness and topped with a crunchy bread crumb crust.
Preheat the oven to 350 degrees.
Slice the squash into small rings.
Layer 1/2 the rings into the bottom of a casserole dish. Top that with 1/2 the onion and 1/3 of the cheese.
Do a second layer on top of the first.
Sprinkle the panko over the top of the casserole.
Pour the butter evenly over the top of the bread crumbs.
Top with the remaining cheese.
Bake, uncovered, for 20 to 30 minutes, or until the top is browned and crisping.