Provençal Tian (Summer squash casserole)

This is modified from a recipe in the Boston Globe food section of July 8 2015. The description says, "Some versions add eggplant, others golden potatoes. Use whatever herbs you have, including oregano, marjoram, and basil."

My reaction is, "This is provençal, right? So of course there should be rosemary too. And it's French, so of course there could be tarragon."

• Olive oil (for sprinkling)
• 2 medium zucchini, trimmed and thinly sliced
• 2 yellow squash, trimmed and thinly sliced
• 3 medium tomatoes, cored and thinly sliced
• Salt and pepper to taste
• 1/2 bunch fresh thyme, leaves chopped
• 6 oz Gruyere or other melting cheese, grated
• 2 T butter
• 1/3 C panko or other dry white unflavored breadcrumbs

Set the oven at 375 degrees. Oil a deep 8- or 9-inch square baking dish.

Put a layer of zucchini in the dish, then a layer of yellow squash, followed by a layer of tomatoes. Sprinkle with salt, pepper, thyme, and cheese. Continue layering until all the vegetables and cheese is used, ending with cheese.

Bake the casserole for 45 minutes.

Meanwhile, in a skillet, melt the butter and cook the breadcrumbs, stirring constantly, for 5 minutes, or until they brown all over.

Remove the casserole from the oven and sprinkle with breadcrumbs. Return it to the oven and continue baking for 5 minutes or until the vegetables are tender when pierced with a skewer.