The traybake is the most oversold dinner of the last decade. Throw everything on a sheet pan, roast, done. Sometimes that works. Often you get pale chicken sitting in a puddle, with courgette that has dissolved and potato still hard in the middle.
Four things decide which version you get.
1. The pan is too full
This is the main one. Vegetables release water as they heat. If they are touching, that water cannot evaporate, so it collects and the pan steams. Steamed food never browns, and browning is the flavour you were after.
Everything needs a little space around it. If your ingredients cover the pan wall to wall, use two pans. An oven can heat two trays perfectly well; it cannot rescue one overloaded one.
2. The oven is not hot enough
Roasting wants 200 to 220°C, fan on if you have it. Below that you are baking, and baking dries food out before it colours.
Preheat properly, including the pan if you have time: food hitting hot metal starts browning on contact instead of slowly warming up. Most home ovens also run cooler than the dial claims, which is worth knowing before you blame the recipe.
3. Everything went in at the same time
A potato needs about forty minutes. Broccoli needs fifteen. Cherry tomatoes need ten. Putting them in together guarantees that something is wrong.
Stagger it:
- Straight away: potatoes, carrots, parsnips, squash, whole shallots, chicken thighs.
- Halfway: peppers, courgette, red onion wedges, sausages if they are thin.
- Last ten minutes: broccoli, tomatoes, chickpeas for crisping, anything green.
- Off the heat: herbs, lemon, cheese, anything you want to taste fresh.
Cut things to sizes that suit the time they get. Potatoes in small cubes catch up with quick vegetables; carrots halved lengthways cook faster than carrots in rounds.
4. Wet things went in wet
Marinades with a lot of soy, juice or yoghurt behave like a poaching liquid in the pan. Drain the marinade off before roasting, or use one that is mostly oil with the flavourings suspended in it.
Pat wet ingredients dry. Rinsed potatoes, drained tinned chickpeas and defrosted anything all carry water that has to leave before browning starts.
The pan itself
Use a heavy, rimmed baking sheet. Thin trays warp in a hot oven and tip everything into one corner, which is how you end up with a burnt half and a raw half. Dark metal browns faster than light metal; glass and ceramic dishes hold heat differently and are better for bakes than for roasting.
Baking paper is fine, but it insulates slightly, so bases brown less. For maximum crunch, oil the metal directly and accept the washing up.
A working formula
Protein plus one root vegetable plus one quick vegetable plus something sharp at the end. Chicken thighs, potatoes, broccoli, lemon. Sausages, squash, red onion, mustard stirred through the pan juices. Halloumi, chickpeas, peppers, a spoon of yoghurt.
Toss everything in enough oil to coat, salt it before it goes in, and give the pan a shake once during cooking so the undersides do not stick and steam.
Finishing
Whatever is left in the pan after roasting is concentrated flavour. Put the tray on the hob over low heat, add a splash of water, wine or stock, and scrape. Thirty seconds later you have a sauce, and the pan is easier to wash than it was a minute ago.
Then add the thing that wakes it up: lemon juice, vinegar, a spoonful of pickle, chopped herbs. Roasted food is sweet and rich, and it almost always wants something sharp next to it.