Curtis Stone says his love for cooking began with his granny's fudge. If there wasn't any in the fridge waiting for him when he came over after school, she'd placate him by making some with him. Slideshow: Fudge Recipes
Grease a 9-by-13-inch baking pan with 2 tablespoons of the butter and scatter the graham crackers evenly over the bottom.
In a large saucepan, combine the remaining stick of butter with the sugar, condensed milk and whole milk. Cook over moderately low heat, brushing down the side of the pan with a wet pastry brush, until the sugar is dissolved, about 12 minutes. Bring the mixture to a simmer, then cook over moderately low heat, stirring occasionally with a wooden spoon, until a pale caramel forms and the temperature reaches 240° on a candy thermometer, about 15 minutes.
Remove the saucepan from the heat. Add the vanilla and a generous pinch of salt to the fudge, and stir vigorously until it thickens but is still pourable, 8 minutes. Immediately scrape the fudge into the prepared pan and spread it evenly with a spatula. Let the fudge cool completely, 1 hour.
Invert the pan onto a surface and tap out the fudge. Break the fudge into pieces and serve.
The fudge can be stored in an airtight container for up to 1 week.