In a large pan, add 3/4 cup butter over medium, allow it to melt, and then boil until it browns. Keep a close eye on the butter so that it does not burn. As soon as you see tiny brown flecks, it is done.
Add 4 cups of granulated sugar and 1 can evaporated milk. Stir until combined and the sugar is melted.
Add a candy thermometer to the mixture and allow the candy to boil until it reaches 234 degrees. Candy will bubble up to twice its size while cooking, so keep an eye on it. If the candy is about to boil over, turn the heat down a bit and stir the mixture until it settles back down.
When the candy reaches 234 degrees, remove it from the heat and add 2 cups white chocolate chips and 1 teaspoon of vanilla extract. Stir with a wooden spoon until combined.
With the wooden spoon, whip the fudge for 3-5 minutes so that it cools and thickens slightly.
Pour the fudge into a greased pan. I like to use the Candy Pan or an 8x8 square pan. Allow the fudge to set for about an hour before slicing.