Scrummy fudge recipe

Fudge is, I think, an expensive thing.  It always seems to cost an amount out of proportion to the humble ingredients of milk, condensed milk, sugar and butter.
The last time I made fudge I think I was about 16 years old.  I was in Rachel Thomas's kitchen and I think it was the summer holidays after 'O' Levels.  I know that recipe used skimmed milk powder and I would love to find that recipe but I fear it might be lost forever.  It seemed so easy.
I promised Hannah that we would make some fudge and found a random recipe on the web.  Most recipes recommended using a sugar thermometer so I bought this.

It's a thermospatula (rubbish name but does what it says on the tin) and you can buy from Lakeland.
You can make fudge without a thermometer but if you get it wrong there's a lot of wasted time, effort and ingredients.
Ingredients

• 400g tin of condensed milk (we used Carnation Light)
• 450g brown sugar (we used light brown sugar)
• 150ml milk (we used skimmed)
• 115g butter (we used unsalted)
• 1 tsp vanilla essence (optional and can be substituted with other flavours)

Method

• Grease and line something roughly 20cm square.
• Heat together the milk, butter and sugar over a low heat in a non stick saucepan for 10-15 minutes.  After this time your bubbling mixture should have reached 115°C and, as the thermometer will show, it is scaldingly hot and needs to be treated with great care.
• If you don't have a thermometer then you will have to test your mixture to see if it has been cooked enough.  This is done by spooning a small amount of the mixture into a cup of cold water.  If it retains its shape then it is ready.  If it just sinks and becomes a blob in the bottom of the cup then it isn't ready.
• Add the vanilla or your choice of flavour and beat for ten minutes until it becomes thick and grainy.  I cheated and put the fudge in the Kenwood and let it take the strain.  If you are going to use a mixer then just be sure you aren't going to spray the scolding mixture anywhere near anyone.
• Ten minutes in the Kenwood is far more effective than ten minutes of beating by hand and by the time I went back to my fudge it was quite thick and stiff but scrapable.  Whether your fudge is scrapable or pourable, transfer it to the prepared container to cool.
• Cool it at room temperature and not in the fridge.
• Once cooled cut or break ready to scoff or share.