Without a baking tray, a rimmed pyrex dish, a cast iron pan, or a rim folded from aluminium foil can largely take over its job; what matters is finding a heatproof, rimmed surface that fits inside the oven.
What does a baking tray actually do?
A baking tray spreads heat evenly and its raised rim keeps dripping liquid or fat from running onto the oven floor, which matters most for saucy dishes and buttery pastries. The tray's material affects the result too: dark metal trays absorb heat faster and speed up cooking, while lighter trays cook more slowly and evenly.
So swapping trays means watching the cooking time rather than trusting the clock.
Which dish can stand in for a tray?
A rimmed glass pyrex dish comes closest to a tray for saucy, liquid-heavy dishes; because glass holds heat more slowly, cooking may run a few minutes longer. A cast iron pan gives better browning underneath for dishes that need frying or charring, though its smaller size may mean using more than one pan for a large batch.
With no tray at all, a thick sheet of aluminium foil folded up at the edges and laid over the oven rack can serve as a makeshift tray, though this only really works for short, low-liquid recipes — over a longer, saucier bake the foil can tear and let liquid reach the oven floor.
What should you watch out for?
With a glass dish, avoid putting a cold dish straight into a hot oven — the sudden change in temperature can crack it, so let it come to room temperature first. With a cast iron pan, its weight can strain the oven rack, so using the bottom rack rather than the middle keeps things balanced.
Whichever alternative you use, dropping the oven temperature by a few degrees and watching the food rather than the clock usually gets a tray-free bake close to the intended result.
What should you watch for when switching between dishes?
Since different dishes hold heat for different lengths of time, resting time after the oven should be adjusted accordingly; a glass dish holds heat longer, so food can keep cooking even after it comes out, meaning it's worth pulling it out a few minutes early. The opposite applies to a cast iron pan, which cools quickly, so if you want the dish served hot, move it to a plate right away.
If more than one alternative dish goes into the oven at once, leave enough space between them; crowded dishes reduce air circulation and can cook unevenly. These small adjustments bring a tray-free oven session as close as possible to the intended result.
Whichever dish you use, its size should fit comfortably inside the oven; a dish placed too close to the door or the heating element can cook unevenly, so it's safer to pick something that sits well in the centre of the oven.
Even with a different dish, the recipe's underlying logic stays the same: adjusting heat and time to match the dish is what brings the result closest to how it would turn out on a tray.