Place the cinnamon, nutmeg, cloves and brown sugar into a large saucepan over a medium heat. Stir regularly until the sugar has fully melted. This should take about 5 minutes. Sugar burns very easily, so make sure you keep an eye on it and stir continuously.
When the sugar has melted, add the white wine, vanilla and orange into the saucepan. The sugar will solidify at the bottom of the pan. Don't worry. Just carry on stirring and the sugar will eventually break off the bottom of the pan and dissolve.
When the sugar has totally dissolved, leave to simmer for 15 minutes. This gives the flavours time to infuse.
Remove the saucepan from the heat and sieve the contents into a serving jug.
Serve immediately or wait until the wine has cooled to room temperature before covering with plastic wrap and storing in the fridge. Enjoy warm or cold - whichever way you prefer!
The longer you leave the flavours to infuse, the better the mulled wine will taste. So if you can prepare in advance, it's worth making this five days before you want to drink it.