Now, let's talk about the magic of emulsification. Emulsification is the process of combining two or more liquids that don't normally mix, like oil and water. In the case of brownies, emulsification helps to create a smooth and creamy texture.
When you use oil instead of butter, you need to make sure that the oil is properly emulsified with the other ingredients. This can be achieved by using an emulsifier like eggs or flaxseed. By doing so, you'll end up with a delicious and fudgy brownie.
Brownies Vegetable Oil Vs Butter at Rebecca Bowens blog