I've got an AMAZING recipe for whiskey fudge that only uses sugar, cream, butter and whiskey... you don't need a thermometer because you can use a glass of water to test once you get to the 'soft ball' stage.
The secret to fudge is all in how you cook it - you're basically trying to stop a chemical reaction that forms large sugar crystals (and gives you that crunchy, crumbly fudge) so that you get smoooooth fudge.
330g caster sugar
100g brown or light brown sugar
125ml cream
60ml milk
40g butter
2 tbsp whiskey
Put all the sugar, cream and milk in a saucepan and mix it all together, then put it on a low heat and don't stir again!! What you need to do now is not agitate the mixture at all, in any way - that's your aim.
Any sugar crystals around the edge of the pan will cause bigger crystals to form as it sets, so have a pastry brush to hand with a cup of hot water and use it to 'brush down' the sides of the pan carefully as your mixture simmers away, so that any sugar crystals move down the pan and back into the mixture.
Let the mixture come to the simmer/boil on this low heat (you don't want any burning) until you get to 'soft ball' which is when little soft balls are formed when you drop the mixture into cold water (just dip a knife in a little and drop some into a glass of water)
Once you get to 'soft ball' move the pan off the heat, put in your chopped up butter (but DON'T stir!) and let it cool, without touching it, for 5ish mins or so. Add whiskey, or any other spirit really (gin fudge anyone?!), then grab a hand-held mixer, or a wooden spoon if you're strong, and BEAT that fudge until you see a def change in texture and it goes milky and harder. Then pour it into a lined tray and leave it to set!
Gasp in awe as you put some into your mouth!