Thoroughly rinse the shrimp under cold water. Drain.
2Heat the 3 tablespoons butter in a small saucepan over medium heat. Blend in flour and salt and pepper. Cook until it bubbles.
Remove from heat and add chicken stock gradually whisking constantly. Bring to a boil, cook for 1 to 2 minutes. Blend in heavy cream and minced onions. mix in raw shrimp.
3Put a layer of the squash in the bottom of 1 1/2 quart casserole with lid, Then cover with half of the shrimp mixture, Repeat layer with squash and remaining shrimp mixture.
4Cover tightly and bake for 30 minutes.
Meanwhile, melt the butter in a small saucepan. Toss in the bread crumbs and parmesan cheese.
5After 30 minutes, Remove the casserole and reduce the oven heat to 350 degrees. Remove cover from casserole an =d top with bread crumb mixture. return to the oven uncovered and cook 15 minutes or until golden brown