Preheat your oven to 160°C/140°C Fan. Grease a 20cm brownie tin or small roasting tin with the butter foil then line the base with baking paper.

Get a large saucepan over a low to medium heat. Dump in the block of butter and let it melt. Once the butter has completely melted start whisking. Within a couple of minutes the butter will have changed from pale yellow to a nutty brown and you will be able to smell it. As soon as it smells nutty take the pan off the heat and leave to cool for 5 minutes. Brown butter done.

Roughly chop any mix-ins you’re using then come back to your butter.

Whisk in the brown sugar until smooth then crack in the eggs, add the vanilla extract, milk and a big pinch of salt. Whisk to combine then add your flour, whisk again. Finally stir through 3/4 of your mix-ins.

Pour the blondie batter into your tin then drop in the remaining mix-ins. Bake in the centre of your oven for 35-40 minutes until the outside is cooked but the centre still has a good wobble - this blondie is so buttery and gooey that the centre will deflate a little once cool. That’s the best bit.

Leave to cool completely in the tin then cut into squares. Will keep for up to 5 days in a container out of the fridge.