Southern Summer Squash Casserole

From the garden

• 2½ lb yellow squash or zucchini, sliced into quarter-inch rounds
• 1 medium sweet onion, diced

From the pantry

• 4 tbsp butter · divided
• 1 cup sour cream
• 1½ cups shredded sharp cheddar
• 2 eggs, beaten
• 1 cup panko or cracker crumbs
• salt · to taste
• black pepper

1. Heat the oven to 375°F and butter a 2-quart baking dish. Melt 2 tablespoons of the butter in a wide skillet over medium-high and cook the squash and onion with a big pinch of salt, stirring occasionally, 10–12 minutes, until the squash is tender and its liquid has cooked off. Wet squash makes a watery casserole, so don't rush this step.
2. Tip the squash into a colander, press gently with a spoon to shed any last liquid, and let it cool 5 minutes so it won't scramble the eggs.
3. Stir the squash together with the sour cream, beaten eggs, 1 cup of the cheddar, a half teaspoon of salt, and plenty of black pepper. Spread into the baking dish.
4. Melt the remaining 2 tablespoons of butter and toss with the panko and the remaining half cup of cheddar. Scatter evenly over the casserole.
5. Bake 30–35 minutes, until the topping is deep golden and the center is set with just a slight jiggle. Rest 10 minutes before serving. It slices cleaner and tastes better slightly cooled.