Add the condensed milk, butter and brown sugar into a saucepan, heat gently and mix until melted.
Keep stirring for 5-10 minutes until the caramel has thickened.
Take off the heat and add in crushed pretzels and press into a lined baking tray (I normally do this whilst still hot before the caramel has set hard).
Melt chocolate, drizzle over the top and finish with a sprinkling of sea salt.
