Grease or line with parchment paper an 8 inch square baking tin. Set aside.
Stove Top Method
If melting with stovetop, place a mixing bowl over a saucepan with simmering water, ensuring the bottom of the bowl doesn’t come into contact with the water. Add the condensed milk, white chocolate and peanut butter. Stir until melted, then remove from heat.
Microwave Method
Add the condensed milk, white chocolate and peanut butter to a microwave safe bowl. Microwave in 30 second blocks, stirring each time, until the chocolate has melted.
Chill
Pour the melted mixture into the prepared pan. If desired, sprinkle with the sea salt flakes, and then place in the fridge to set for 2 hours.
Once the fudge has set, slice with a sharp knife and enjoy!