This is taken from deliaonline forum, but it is a recipe that most of us sweetie people are familiar with and have used for many years. (I can't find mine!)
FUDGE
8 oz butter
Large tin condensed milk
1 lb white sugar
Melt butter and sugar in a large heavy-based pan. Add milk. Stir until boiling. Simmer, stirring occasionally, until thick, light brown in colour and has reached 'soft ball' temperature. Simmer fairly gently or it will burn! This may take 30 minutes +. Take off the heat and beat hard until it thickens and becomes 'grainy'. Pour into a greased tin or onto baking parchment. Leave to cool then cut and enjoy.