In a heavy-bottomed pan, bring the sugar and milk to a boil. Continue to cook for five minutes on a medium heat, stirring regularly to ensure the mixture doesn't stick.

Remove the pan from the heat and add the condensed milk, returning to the heat and allowing to boil once more. Continue to boil for around 20 minutes, stirring continuously, until the fudge is very thick.

Remove from the heat and beat in the butter and vanilla for around 4-7 minutes (the longer you beat it, the firmer the fudge will turn out).

Throw the Oreos into the fudge (keeping back a tablespoon or so to sprinkle on top) and quickly stir them into the mixture. Pour into a tin lined with grease-proof paper and sprinkle with the white chocolate and remaining Oreo pieces. 

Place the tin in the fridge until set (it shouldn't take very long) and when completely cooled and hardened, cut into squares. Enjoy!