Try this delicous treat when you take home your CSA basket this week.
Preheat an oven to 350°F. Butter a 9-by-13-inch baking dish.
- 6 tbsps unsalted butter (plus more for greasing pan)
- 1/3 cup all-purpose flour
- 3 cups half & half
- 1 bay leaf
- 1 tbsp minced garlic
- freshly ground pepper (Kosher salt and, to taste)
- 2 tsps chopped fresh thyme
- 3 tbsps flat leaf parsley (chopped)
- 1 tbsp olive oil
- 1 yellow onion (thinly sliced)
- 5 zucchini (about 1 1/2 lb. total, peeled into wide, thin sheets)
- 6 yellow squash (about 1 1/2 lb. total, peeled into wide, thin sheets)
- 2 russet potatoes (skin peeled and discarded, potatoes peeled into wide, thin sheets)
- 1 cup parmigiano reggiano cheese (finely grated)
Preheat an oven to 350°F. Butter a 9-by-13-inch baking dish.In a saucepan over medium heat, melt the 6 Tbs. butter. Stir in the flour to make a paste and cook, stirring occasionally, for 2 minutes. Whisk in the half-and-half, bay leaf and garlic until no lumps remain. Bring to a simmer and cook, stirring occasionally, until thickened, about 3 minutes. Remove the bay leaf and discard. Season the sauce with salt and pepper. Stir in the thyme and parsley. Let the sauce cool to room temperature.In a sauté pan over medium-high heat, warm the olive oil. Add the onion and cook, stirring occasionally, until lightly browned and tender, about 10 minutes, adjusting the heat as needed to prevent overbrowning. Remove from the heat.To assemble the gratin, layer one-third of the squash (both zucchini and yellow squash) in the bottom of the prepared baking dish. Top with half of the onion, half of the potatoes and 1/3 cup of the cheese. Spread 1 cup of the sauce on top. Repeat the layering with one-third of the squash, the remaining onion and potatoes and 1/3 cup of the cheese. Spread 1 cup of the sauce on top. Layer the remaining squash on top, spread the remaining sauce over the squash and sprinkle with the remaining cheese.Transfer the baking dish to the oven. Bake until the squash and potatoes are tender and the top is golden brown, about 1 hour. Serves 10 to 12.