Short answer: push a thin metal cake tester into the very centre and pull it out. Clean, or a couple of dry crumbs, means it’s done. Wet batter means give it another five minutes and test again.

Why bother with a proper tester? Because the recipe says 45 minutes. The top is golden, it’s pulling away from the sides a bit, and it smells done. Then you cut into it and the middle is a sticky, sunken mess. Ovens run hot or cold, tins vary, and a recipe’s timing is only ever a starting point.

What to push in

For sponges, loaf cakes and fruit cakes, the poke test beats any timer. The tricky part is what you poke with. A cocktail stick is too short for a deep loaf or a Christmas cake. A knife leaves a gash in the top. A wooden kebab skewer works, but it’s rough enough that crumbs stick to it even when the cake is done, so you can’t tell what you’re looking at.

Cake testers fix all three. They’re very thin, smooth metal wires with a handle on the end. They leave a hole you can barely see, and wet batter is obvious on shiny steel.

The Ateco testers

Ateco make a lot of professional cake decorating gear, and their Stainless Steel Cake Tester comes as a set of three. Each one is 7 inches long, a fine stainless steel wire with a flat blue handle at the top. Seven inches is long enough to reach the middle of a deep loaf tin, and the bright handles are easy to spot in a drawer full of utensils, which matters more than you’d think with something this thin. You can find the Ateco set on Amazon.

Three might sound like a lot. One lives with the baking tins, one with the cooking utensils, and one inevitably goes missing.

When a tester won’t help you

Some bakes are meant to be gooey. A tester in a brownie will come out sticky even when it’s right, so go by the crust and a slight wobble instead. Cheesecake is the same. For bread, a tester tells you very little; tap the base and listen for a hollow sound, or use a probe thermometer.

Fruit cakes are where it earns its keep. They’re deep and dense, they bake for hours, and the outside looks done long before the middle is.