Community recipe
Golden Zucchini-Corn Gratin with Cheddar Biscuit Crust
A cozy summer-vegetable bake with tender zucchini, sweet corn, and a savory cheddar biscuit lid that turns golden and crisp at the edges. Salting the zucchini first keeps the creamy filling rich rather than watery; a little mustard and fresh thyme give the familiar gratin a bright, savory lift. Serve warm as a satisfying vegetarian main or a generous side.
- Serves
- 6
- Prep
- 25 min
- Cook
- 40 min
- Difficulty
- medium
Get ready
Ingredients
- 2 lb zucchinis, rinsed, dried, ends trimmed, cut into 1/4-inch half-moons
- 1 tsp fine salt
- 1 tsp unsalted butter, softened, for greasing
- 1 yellow onion, small, peeled and finely chopped
- 2 garlic cloves, peeled and finely chopped
- 1 tbsp fresh thyme leaf, stripped from stems and chopped
- 1.5 cup corn kernels, drained if canned or thawed
- 1.5 cup sharp cheddar cheese, grated; reserve 1/2 cup for topping
- 1 tbsp olive oil
- 0.5 cup heavy cream
- 1 tsp dijon mustard
- 0.25 tsp black pepper
- 0.25 tsp fine salt, for final seasoning, add only as needed (optional)
- 1 cup all-purpose flour
- 1 tsp baking powder
- 0.25 tsp fine salt
- 3 tbsp unsalted butter, cold, cut into small cubes
- 0.33 cup whole milk
Make it
Instructions
- 01
Salt and drain the zucchini
Set a colander over a bowl and line a rimmed tray with a clean kitchen towel. Rinse and dry 2 lb zucchini, trim the ends, and cut into 1/4-inch half-moons. Toss with 1 tsp fine salt, spread in the colander, and leave for 20 minutes while you prepare the other ingredients. Pat the zucchini very dry with the towel before cooking. | Why: Removing excess moisture helps the gratin bake up creamy, not watery.
- 02
Prepare the oven, dish, and vegetables
While the zucchini drains, place a rack in the center of the oven and heat it to 400°F (200°C). Lightly butter a 9-by-13-inch baking dish with 1 tsp unsalted butter. Peel and finely chop 1 small yellow onion and 2 garlic cloves. Strip and chop 1 tbsp fresh thyme leaves; drain 1 1/2 cups corn kernels if using canned or thawed corn. Grate 1 1/2 cups sharp cheddar cheese, setting aside 1/2 cup for the topping. | Why: Getting the oven and filling components ready keeps assembly quick and even.
- 03
Cook the vegetables and make the creamy filling
Heat a large skillet over medium-high heat and add 1 tbsp olive oil. Add the drained zucchini and cook, stirring occasionally, for 6–8 minutes until tender with a few golden edges; transfer it to a plate. Add 1 tbsp olive oil to the skillet, then cook the onion for 4–5 minutes until soft and translucent. Stir in the garlic and thyme for 30 seconds, just until fragrant. Add the corn and cook for 2 minutes. Stir in 1/2 cup heavy cream, 1 tsp Dijon mustard, and 1/4 tsp black pepper; simmer gently for 1 minute. Fold in the cooked zucchini and 1 cup of the grated cheddar, then remove from the heat. Taste and add up to 1/4 tsp fine salt if needed, remembering the zucchini was salted and the cheese is savory. | Why: Briefly cooking off liquid and seasoning the filling builds concentrated flavor before baking.
- 04
Mix the cheddar biscuit topping
In a medium bowl, whisk 1 cup all-purpose flour, 1 tsp baking powder, and 1/4 tsp fine salt. Cut in 3 tbsp cold unsalted butter, using your fingertips or a pastry cutter, until the mixture has pea-size crumbs. Stir in the reserved 1/2 cup cheddar and 1/3 cup whole milk just until a shaggy, soft dough forms; do not overmix. | Why: A lightly handled dough bakes into a tender biscuit crust with crisp golden tops.
- 05
Top and bake the gratin
Spoon the zucchini-corn mixture into the buttered baking dish and spread it evenly. Drop small, walnut-size portions of biscuit dough across the surface, leaving a little space between them so steam can escape. Bake on the center rack at 400°F (200°C) for 22–27 minutes, until the filling bubbles at the edges and the biscuit tops are puffed and deep golden. If the tops brown too quickly, loosely cover the dish with foil for the remaining bake time. | Why: The open spaces let the filling bubble while the biscuit portions brown and cook through.
- 06
Rest and serve
Set the hot dish on a heat-safe surface and let it rest for 10 minutes so the creamy filling settles. Serve warm, scooping through the tender vegetables and golden biscuit crust in each portion. | Why: A short rest helps the gratin hold together without losing its creamy texture.
