Prepare the base: In a medium saucepan (off the heat), whisk together the sugar, cornflour, and salt. Make sure there are no lumps of cornflour — run the back of a spoon through the mixture if needed. The dry mix should feel like fine, powdery sand between your fingers.

Add the wet ingredients: In a small bowl, lightly beat the egg yolks with a fork until they are an even, bright yellow colour. Pour the whole milk and the beaten yolks into the saucepan with the dry ingredients. Whisk everything together until the mixture is completely smooth and looks like thin, pale cream.

Cook over medium heat: Place the saucepan on the hob over a medium heat. Whisk continuously — do not stop, or lumps will form. After about 3 to 4 minutes, you will feel the mixture start to thicken at the bottom of the pan. The sound will change from a sloshing liquid to a gentle, bubbling murmur.

Watch for the first bubble: Keep whisking. After another 2 minutes, you will see the first few lazy bubbles break the surface. The mixture will now be noticeably thicker, coating the back of your spoon. When you lift the whisk, the pudding should fall in a thick, wide ribbon that sits on top of itself for a moment before sinking back in.

Boil for 60 seconds: Once the mixture is bubbling steadily, let it cook for exactly 60 seconds while whisking constantly. This step is crucial — it cooks the cornflour fully and ensures a silky, non-starchy finish. The pudding will look glossy and feel heavy on the whisk.

Finish with butter and vanilla: Remove the saucepan from the heat immediately. Drop in the diced butter and the vanilla extract. Whisk gently until the butter has melted completely and the pudding is shiny and smooth. The aroma of warm vanilla will fill your kitchen at this stage.

Transfer and cool: Pour the pudding into four small serving bowls or ramekins. Press a piece of cling film directly onto the surface of each pudding — this stops a skin from forming as it cools. Let them sit at room temperature for 10 minutes, then refrigerate for at least 2 hours if you want a firmer, chilled pudding. If you are serving it warm, leave the cling film off and let it sit for just 5 minutes before digging in.