Add the brown sugar, granulated sugar, butter, cream and salt to a medium-sized pot over medium heat. Stir until butter and sugar are melted and combined. Stop stirring
Continue cooking until candy mixture starts to bubble and reaches a temperature using a candy thermometer of 236F. Test using the soft ball method by adding some of the candy mixture to a cup of cold water. If a soft candy ball forms than the fudge is cooked.
Remove from heat and let cool to 110F. Once cooled add the vanilla and quickly beat with a wooden spoon until the fudge becomes smooth, lighter in colour and loses it shininess to a matte texture.
Pour the fudge quickly into an 8" X 8" glass dish lined with parchment paper. Push the fudge into the corners of the pan with the wooden spoon or spatula and smooth off the top. Let cool completely for about 1 hour and then cut into squares.
Store in a sealed container on the counter for up to 3 weeks.
Can be stored on the counter for up to 3 weeks in a tightly sealed container.Substitutions:Heavy whipping cream can be substituted for evaporated milkAdd-ons:Pecans or walnuts can be added at the same time vanilla is added. A 1/4 cup will do.