You will need butter for many different recipes in Genshin Impact, so knowing where to get it will be helpful. You cannot find butter, or buy it, and instead will need to make it for yourself.
Butter can be processed at any cooking pot or food stall in the game, as long as you have the correct ingredient. To make butter, you will need milk. You can purchase milk from Blanche, the shopkeeper at MOndstadt General Goods. It will cost 100 Mora per bottle, and you will need two bottles to make one stick of butter.
When you have the milk, turn around and head for the large cooking pot on the right of the Good Hunter to process the milk into butter.
How to process ingredients
To process ingredients, you will need to find a cooking fire that will allow you to cook. You can once again find these all over the map, including in the many towns that you will find. They will be marked by a spoon and fork symbol on the minimap, and you can find one in Mondstadt, the first town that you will end up visiting.
Interact with the cooking fire and then switch to the second tab, which is called Process. Here you will get a list of the ingredients that you have in your inventory that you can actually process. All you need to do to process the item is to select it, enter the amount of it you wish to process, and then wait while it happens.
All ingredients have a timer for processing, which could be up to a minute or more. For butter, it will take four minutes per stick. You can queue up lots of items for processing, then go and play a different part of the game, and return later to collect all your processed ingredients. Just interact with the cooking fire, go to Process, and then hit the prompted button to obtain your processed ingredients. You will need plenty of processed ingredients to cook some of the game’s more complex recipes.