Zucchini Gratin with Gruyère and Panko Breadcrumbs

INGREDIENTS

2 lb

(3-4) zucchini, sliced into ¼ inch pieces

large bell pepper, sliced

large onion, sliced

1 tbsp

unsalted butter

Salt and pepper,

4 tbsp

unsalted butter

4 tbsp

all-purpose flour

2 1/2 cups

milk (I used 2%)

1/4 tsp

ground nutmeg

Salt and pepper,

1 cup

Panko breadcrumbs, divided

1 cup

Gruyère cheese, shredded

1 tbsp

unsalted butter