Tips for Summer Squash Casserole Success
Summer squash is composed mostly of water, which is really important to remember when building a casserole (otherwise known as a gratin) around this healthy and beautiful vegetable.
Too many times my summer squash casseroles are watery and flavorless. I decided to take on this challenge and see if I couldn’t correct this issue. Thanks to the folks at America’s Test Kitchen, I found the secrets to a non-watery and flavor-packed summer squash casserole!
First, they figured out how to remove the excess water from zucchini and summer squash and keep the crumb topping nice and crisp. First they tossed 3 pounds of sliced squash with 2 teaspoons of salt and zapped the vegetable in the microwave. 8 minutes drew out excess water without destroying the squash.
The test kitchen pros explain why this works: “Salt draws out moisture by osmosis, but the water needs time to cross many cell walls. Microwaving breaks down cell walls. Since the water runs into fewer barriers, it comes out faster.”
After they removed the squash from the microwave, they drained the slices and pressed them dry. Then they started combining ingredients. Good squash casseroles seem to have one thing in common—bread crumbs. But a bread-crumb-secret? You want them extra crispy to start with so they have a chance of staying crispy during and after baking. So the Test Kitchen cooks opted for crispy Panko crumbs tossed with grated Parmesan cheese.
And here’s the next big secret: I also learned from the Test Kitchen cooks that instead of just topping the casserole with crumbs, it’s important to employ them throughout—crumbs layered on the bottom, in the middle layer, as well as on the top absorb moisture released by the baking squash.
Another important secret these cooks shared was that after the casserole bakes (covered), for 15 minutes, you add a final top layer of crumbs, which browns, but doesn’t soak into the dish, and then bake for a final 15 minutes.
The final secret these cooks shared: You want to layer the squash slices with nicely caramelized onions and garlic, thyme, kalamata olives, and fresh basil. The conclusion? “Combined, these assertive seasonings proved perfect foils for relatively bland summer squash!” reports the Test Kitchen pros.
Filled with confidence and hope, I tried their suggestions and dared to serve yet another squash casserole at a family dinner last week. I was rewarded for my effort by oohs and aahs as they polished off two 9x13s of this super recipe. Many thanks to America’s Test Kitchen cooks for sharing their secrets. Now if you want to make a non-watery squash casserole yourself, here’s their delicious recipe:
2 tablespoons unsalted butter softened, plus 4 tablespoons melted
2 onions halved and sliced thin
salt and pepper to taste
3 cloves garlic minced
1 tablespoon minced fresh thyme
1/2 cup dry white wine
1/2 cup pitted Kalamata olives chopped fine
1/4 cup chopped fresh basil divided
1 1/2 pounds zucchini sliced 1/4-inch thick
1 1/2 pounds yellow summer squash sliced 1/4-inch thick
1 1/4 cups crispy panko bread crumbs
1 1/4 cups grated Parmesan cheese
Directions:
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Too many times my summer squash casseroles are watery and flavorless. I decided to take on this challenge and see if I couldn’t correct this issue. Thanks to the folks at America’s Test Kitchen, I found the secrets to a non-watery and flavor-packed summer squash casserole!
First, they figured out how to remove the excess water from zucchini and summer squash and keep the crumb topping nice and crisp. First they tossed 3 pounds of sliced squash with 2 teaspoons of salt and zapped the vegetable in the microwave. 8 minutes drew out excess water without destroying the squash.
The test kitchen pros explain why this works: “Salt draws out moisture by osmosis, but the water needs time to cross many cell walls. Microwaving breaks down cell walls. Since the water runs into fewer barriers, it comes out faster.”
After they removed the squash from the microwave, they drained the slices and pressed them dry. Then they started combining ingredients. Good squash casseroles seem to have one thing in common—bread crumbs. But a bread-crumb-secret? You want them extra crispy to start with so they have a chance of staying crispy during and after baking. So the Test Kitchen cooks opted for crispy Panko crumbs tossed with grated Parmesan cheese.
And here’s the next big secret: I also learned from the Test Kitchen cooks that instead of just topping the casserole with crumbs, it’s important to employ them throughout—crumbs layered on the bottom, in the middle layer, as well as on the top absorb moisture released by the baking squash.
Another important secret these cooks shared was that after the casserole bakes (covered), for 15 minutes, you add a final top layer of crumbs, which browns, but doesn’t soak into the dish, and then bake for a final 15 minutes.
The final secret these cooks shared: You want to layer the squash slices with nicely caramelized onions and garlic, thyme, kalamata olives, and fresh basil. The conclusion? “Combined, these assertive seasonings proved perfect foils for relatively bland summer squash!” reports the Test Kitchen pros.
Filled with confidence and hope, I tried their suggestions and dared to serve yet another squash casserole at a family dinner last week. I was rewarded for my effort by oohs and aahs as they polished off two 9x13s of this super recipe. Many thanks to America’s Test Kitchen cooks for sharing their secrets. Now if you want to make a non-watery squash casserole yourself, here’s their delicious recipe:
Summer Squash Gratin
Serving size: 6
Calories per serving: 338
Ingredients:
Calories per serving: 338
2 tablespoons unsalted butter softened, plus 4 tablespoons melted
2 onions halved and sliced thin
salt and pepper to taste
3 cloves garlic minced
1 tablespoon minced fresh thyme
1/2 cup dry white wine
1/2 cup pitted Kalamata olives chopped fine
1/4 cup chopped fresh basil divided
1 1/2 pounds zucchini sliced 1/4-inch thick
1 1/2 pounds yellow summer squash sliced 1/4-inch thick
1 1/4 cups crispy panko bread crumbs
1 1/4 cups grated Parmesan cheese
Directions:
Melt 1 tablespoon softened butter in 12-inch nonstick skillet over medium heat. Add onions, 1/2 teaspoon salt, and 1/4 teaspoon pepper and cook, stirring occasionally, until onions are soft and golden brown, 15 to 20 minutes. Stir in garlic and thyme and cook until fragrant, about 30 seconds. Stir in wine and cook until evaporated, about 3 minutes. Off heat, stir in olives and 2 tablespoons basil; set aside.
Meanwhile, toss zucchini and yellow squash with 2 teaspoons salt in large bowl. Microwave, covered, stirring halfway through microwaving, until slightly softened and some liquid is released, about 8 minutes. Drain in colander and let cool slightly. Arrange zucchini and yellow squash on tripled layer of paper towels, then cover with another triple layer of paper towels. Press slices firmly to remove as much liquid as possible.
Adjust oven rack to middle position and heat oven to 450°. Grease bottom and sides of 13x9-inch baking dish with remaining 1 tablespoon softened butter. Combine panko, Paremesan, and 1 teaspoon pepper in bowl. Evenly coat baking dish with 6 tablespoons panko mixture. Stir melted butter into remaining panko mixture until well combined; set aside.
Arrange half of squash in prepared dish and season with pepper to taste. Sprinkle 1/4 cup panko mixture evenly over squash. Spread onion mixture in even layer over crumbs. Arrange remaining half of squash over onion mixture and season with pepper to taste. Cover with aluminum foil and bake until just tender, about 15 minutes.
Remove dish from oven; discard foil. Sprinkle remaining panko mixture evenly over top. Bake, uncovered, until bubbling around edges and crumbs are golden brown, 10 to 15 minutes. Transfer to wire rack and let cool for 15 minutes. Sprinkle with remaining 2 tablespoons basil. Serve.
Meanwhile, toss zucchini and yellow squash with 2 teaspoons salt in large bowl. Microwave, covered, stirring halfway through microwaving, until slightly softened and some liquid is released, about 8 minutes. Drain in colander and let cool slightly. Arrange zucchini and yellow squash on tripled layer of paper towels, then cover with another triple layer of paper towels. Press slices firmly to remove as much liquid as possible.
Adjust oven rack to middle position and heat oven to 450°. Grease bottom and sides of 13x9-inch baking dish with remaining 1 tablespoon softened butter. Combine panko, Paremesan, and 1 teaspoon pepper in bowl. Evenly coat baking dish with 6 tablespoons panko mixture. Stir melted butter into remaining panko mixture until well combined; set aside.
Arrange half of squash in prepared dish and season with pepper to taste. Sprinkle 1/4 cup panko mixture evenly over squash. Spread onion mixture in even layer over crumbs. Arrange remaining half of squash over onion mixture and season with pepper to taste. Cover with aluminum foil and bake until just tender, about 15 minutes.
Remove dish from oven; discard foil. Sprinkle remaining panko mixture evenly over top. Bake, uncovered, until bubbling around edges and crumbs are golden brown, 10 to 15 minutes. Transfer to wire rack and let cool for 15 minutes. Sprinkle with remaining 2 tablespoons basil. Serve.
Recipe formatted with the Cook'n Recipe Software from DVO Enterprises.
Sources:
- www.thekitchn.com
- www.hearldtribune.com
- www.healthyheartmarket.com
- www.brit.co
- www.cookscountry.com
Alice Osborne
Weekly Newsletter Contributor since 2006
Email the author! alice@dvo.com
