Place sugar and full fat milk into large pan. Place over a gentle heat and stir occasionally until all the sugar is dissolved.
Once all sugar is dissolved add butter and allow to melt. Once butter is melted add condensed milk, mix in well. Increase the heat and stir continuously while mixture boils until it has reached Soft-Ball Stage - 120 degrees C / 240 degrees F (I use a sugar thermometer).
Allow mixture to settle and add a few drops of vanilla.
Beat mixture (I use a hand held beater) until it is almost setting in pot. Pour mixture into a well greased swiss roll tin and allow to set.
After 30 or so minutes I score the size of pieces I want, this makes it easier to finally cut the tablet when it is set.
Gas cookers / hobs melt the milk and sugar mixture far faster.
Use a sugar thermometer until you know what almost ready tablet looks like; this avoid disasters.
Be careful the boiling mixture is very hot.
Good recipe, some extra tips..
1) You need to be careful of temperature shown. Soft Ball (i.e. Tablet/Fudges) is 112-116C and Firm Ball (i.e. Caramel) is 118-120C so once you reach 116C reduce the hob temperature to keep it around there, if it creeps up too far then the tablet won't set (a darker colour will also indicate too high a temperature).
2) For lazy people like me I find an Electric whisk works very well (but probably not if you are using a non-stick pan!)
3) Before adding the vanilla essence ensure the temperature has fallen below 100C otherwise it will simply boil off!
4) For an improved vanilla flavour plan ahead, put your sugar in an airtight container with 2 split vanilla pods some weeks (or even months) before you plan to make your tablet. It will improve the richness of the flavour. - 02 Mar 2015