1. Prepare the Pan

1. Line an 8×8-inch baking pan with parchment paper or aluminum foil, leaving an overhang for easy removal.

2. Make the Caramel Base

1. In a medium saucepan, combine sweetened condensed milk, sugar, butter, and heavy cream.
2. Heat over medium heat, stirring constantly, until the mixture begins to melt and come to a simmer.
3. Once simmering, reduce the heat slightly and continue stirring for 5-7 minutes until the mixture thickens and becomes smooth.

3. Add Flavor and Chocolate

1. Remove the saucepan from the heat and stir in the vanilla extract and sea salt.
2. Add the white chocolate chips and milk chocolate chips. Stir until the chips are completely melted and the mixture is smooth and glossy.

4. Set the Fudge

1. Pour the fudge mixture into the prepared baking pan, spreading it evenly with a spatula.
2. Sprinkle a little extra sea salt over the top for that salty-sweet balance.

5. Chill and Slice

1. Refrigerate the fudge for at least 2 hours, or until firm enough to slice.
2. Once set, use the parchment paper overhang to lift the fudge out of the pan. Cut into 16 squares or bars.