1-Step 1: Prep the Zucchini Grate the 1 large zucchini (about 0.5 lb / 227 g) directly into a colander. Sprinkle 1/2 teaspoon salt (≈ 2.5 mL) over it and let sit at least 30 minutes to draw out moisture. Squeeze out as much liquid as possible. For best results, do this the night before and store in a sealed bag in the fridge.

2-Step 2: Preheat and Prep Other Items Preheat oven to 400°F (≈ 204°C). Dice the 1/4 medium onion. Shred the 4 ounces (113 g) of cheddar from a block for best melting.

3-Step 3: Mix the Batter In a mixing bowl, combine the drained grated zucchini, diced onion, about two-thirds of the shredded cheddar (≈ 76 g), the 8-ounce (227 g) corn muffin mix, 1 large egg, and 1/3 cup (≈ 79 mL) milk. Stir until incorporated, taking care not to overmix. This keeps your zucchini cornbread casserole with cheddar cheese nice and tender.

4-Step 4: Assemble in Pan Pour the batter into an 8 × 8-inch (20 × 20 cm) baking pan. Sprinkle the remaining shredded cheddar (about one-third, ≈ 37 g) evenly over the top.

5-Step 5: Bake Bake 25 30 minutes, until set, edges start to brown, and top cheese begins to brown. Total cook time is quick, perfect for weeknights.

6-Step 6: Cool and Serve Let the casserole cool in the pan about 30 minutes before slicing into 16 pieces. Serve hot or cold. Prep time: about 5 minutes (plus 30 minutes for zucchini draining). Total time: approximately 1 hour including draining and cooling.

7-Step 7: Optional Twists Fold in sweet corn kernels or fresh herbs like chives before mixing for that summer zucchini and sweet corn casserole vibe. Pair it with easy chicken spaghetti for a full meal.