Zucchini and Tomato Gratin

The weather is getting warmer here in the UK which has me dreaming of garden vegetables and this Zucchini and Tomato Gratin I made late last summer. At the end of the season there is always a glut of vegetables especially and happily zucchinis and tomatoes. I love this gratin because it puts the vegetables front and center. Nestle a poached egg or two into the cooked gratin and it is a complete meal. Or finish it with a dusting of grated parmesan cheese and pop it under the broiler (grill) for a minute to brown.

I like to zebra stripe the zucchini before cooking it. Using a vegetable peeler remove alternating strips of the skin down the length of each squash about 1/4 to 1/2 inch wide. This leaves a pretty green/white alternating pattern. A mandoline is useful, but not necessary, to slice the zucchini into rounds of about 1/8 inch thick.

The cooked onions provide an essential flavor base for the zucchini and tomato gratin so don’t skip this step. You can set them to cook on low heat while you slice the vegetables. Find more vegetable recipes here.

Adrienne and I made lots of gratins like this one often incorporating eggplant as well. I came across her inspiration for these summer vegetable gratins when I was researching recipes for my next book, Cooking with my Friends. Adrienne and her husband spent many summers in the South of France and often ate at Roger Vergé’s restaurant, Moulin de Mougin. It was in his book, Cuisine of the Sun, that I found almost exactly the same recipe Adrienne and I had making for years.

A super easy gratin makes the most of zucchini and tomatoes at the end of the summer

1 large onion (about 6 ounces)
5 small zucchini (about 1 1/4 pounds)
5-6 small ripe tomatoes (about 1 1/2 pounds)
1 large garlic clove (peeled)
1/2 tsp thyme leaves (fresh or dried)
olive oil
Salt & Pepper
1 ounce Parmesan cheese (grated (optional))

475 F
Cut the onion into very thin slices. Heat two tablespoons of olive oil in a small sauté pan. When the oil is hot, lower the heat and cook the onion until soft but not browned.
Using a vegetable peeler remove long thin strips of the skin from the top to the bottom of the squash, about 1/4" – 1/2" wide and at 1/2" intervals. The result is alternating pattern of green and white stipes. Slice the zucchini into 1/8 inch rounds. Set aside.
With a small knife remove the core from each tomato and cut them vertically into slices about 1/4" thick. Set aside.
Rub the bottom and sides of a 9"x10" gratin dish or casserole with the garlic clove, pressing down hard to release its juice. Cut the remainder of the clove into slices. Then line the dish with the cooked onion. Arrange long overlapping rows of the zucchini and tomatoes forming alternating bands of red and green (see photo). Tuck the garlic slices in between the vegetables. Season with salt and pepper and scatter the thyme leaves over all. Drizzle with olive oil.
Place the dish in the oven and bake 30-35 minutes. After the first 15 minutes lightly drizzle again with olive oil. After 20 minutes sprinkle grated parmesan cheese on top. When cooked the vegetables should be soft and slightly browned.