Summer Squash Gratin with Salsa Verde and Cheese

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 

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