Serves 4 

Salsa Verde: 
1 teaspoon fresh marjoram or oregano leaves (1/2 teaspoon dried)
1/4 cup coarsely chopped mint 
1 cup coarsely chopped flat-leaf parsley 
3/4 cups extra-virgin olive oil 
1 small clove garlic 
1 tablespoon capers, drained (rinsed if salt-packed) 
1/2 lemon, for juicing 
Freshly ground black pepper 

Gratin: 
2 pounds summer squash 
1 1/2 cup fresh breadcrumbs 
3 tablespoons unsalted butter (or mix half olive oil/half butter) 
3/4 cups sliced shallot or leek 
1 teaspoon minced garlic 
1 tablespoon basil leaves 
1 cup grated Gruyere or Comte or cheddar or jack cheese 
Kosher salt and freshly ground black pepper 

Make the salsa verde. Using a mortar and pestle (or a food processor, I won't tell anyone), pound the herbs to a paste. You may have to do this in batches. Work in some of the olive oil, and transfer the mixture to a bowl. Gently pound the capers until they're partially crushed, and add them to the herbs. Stir in the remaining oil, a pinch of black pepper, and a squeeze of lemon juice. Taste for balance and seasoning.

Make the gratin. Heat the oven to 400º. Cut the squash into 1/8-inch-thick slices. Toss the slices in a large bowl with 1 teaspoon kosher salt, and let sit 10 minutes.

Place the breadcrumbs in a bowl. Heat a small saute pan over medium heat for 1 minutes. Swirl in the butter/oil and cook for a few minutes, until it browns and smells nutty. Pour the brown butter over the breadcrumbs (being sure to scrape all the brown bits into the bowl with a rubber spatula). Wait a minute or so for the butter to cool, and toss well.

Drain the squash and transfer it to a large mixing bowl. Add the shallots, minced garlic, basil, 1/2 cup salsa verde, and some pepper. Toss to combine, and add the cheese and half the butter-coated breadcrumbs. Toss again, and taste for seasoning. (The raw garlic will taste strong at this point but will be delicious when cooked.)

Place the squash in a gratin dish (you can use an over-proof skillet for a rustic presentation). Scatter the remaining breadcrumbs over the top, and bake 35 to 40 minutes, until the squash is tender and the top is crisp.

Adapted from Amanda at Food 52.com