Pat zucchini and mushrooms completely dry with paper towels before roasting—excess moisture prevents caramelization and creates steam instead of browning.

Slice zucchini into uniform ¼-inch rounds and quarter mushrooms to similar sizes so everything roasts at the same rate without dry or undercooked pieces.

Arrange vegetables in a single layer with space between pieces—crowding creates steam and prevents the golden caramelization that makes this dish special.

Toss vegetables with salt, pepper, and olive oil before roasting, then add fresh thyme halfway through cooking to preserve its delicate flavor and aroma.

Roast at 425°F or higher to achieve proper browning and sweet caramelization in just 25 minutes—lower temperatures result in soft, steamed vegetables.