Put the butter into a saucepan and melt it over a low heat, remove from the heat and set aside
Turn on your waffles maker so it can heat up, I put mine on the max heat setting, but all waffle makers are different
In a large mixing bowl, add the plain flour, caster sugar and baking powder. Stir them together until well combined
In another bowl, or a jug, add the milk, eggs and vanilla extract. Gently whisk them together until combined
Pour the milk mixture into the flour mixture, whisking as you pour, and keep whisking until the batter is smooth
Then add the melted butter bit by bit, whisking between each addition, until the batter is smooth and shiny
I prefer to transfer the batter into a jug so I can easily pour it into my waffle maker, but you can also use a spoon to spoon it into the waffle maker as well
Pour some of the batter into your waffle maker, you want the little squares to be covered but still just about visible through the batter. If you're not sure how much to, it's better to add too little and then increase the amount as you go. If the batter does spill out the sides don't worry, just wipe it away
Gently close the lid of the waffle maker, do not push it down. The waffles will take around 4-5 minutes, but you can check on them from 3 minutes
Once the waffle is cooked to your liking, carefully remove it from the waffle maker, I use silicone tongs to do this, and place on a cooling rack
Repeat until all of the batter is used up
The waffles will seem soft when you first remove them from the waffle maker, but they will crisp up quickly as they start to cool
Serve immediately, or allow to cool and store in the fridge or freeze them to enjoy another time