Zucchini Gratin

This is a really easy recipe that comes from the cookbook "Sunday Suppers at Lucques". It's pretty much layer the ingredients and bake, but I like to verge off from the original recipe a bit, and saute the onions in the olive oil for a little while to get them carmelized  - I think it makes a big difference in the finished product - before topping with the zucchini and the kosher salt)

• 3 onions, sliced
• olive oil
• 2 large zucchini, sliced into rounds
• basket of cherry tomatoes (not grape tomatoes)
• 1/2 cup of grated Parmesan or Romano cheese, divided in half
• 1/2 cup of fresh breadcrumbs, divided in half
• fresh basil leaves and kosher salt

Pour olive oil on the bottom of a 12" cast iron skillet.
Layer 1/2 of the onions on the bottom, then top with 1/2 of the zucchini. Sprinkle a little kosher salt on top.
Sprinkle 1/4 cup of the cheese on the zucchini, then 1/4 cup of the breadcrumbs.
Drizzle with olive oil. Scatter the cherry tomatoes around.
Repeat with another layer of onions, zucchini, cheese, breadcrumbs, oil and tomatoes.
Finish with basil leaves and bake in a 425F oven for about 30 minutes until the skillet is bubbling!
** Put under the broiler for a few minutes if you want it more brown on top. Wait about 20 minutes before serving.