Line a 20 x 20cm cake tin with baking parchment. Tip the sugar, cream, butter and glucose syrup into a large pan. Warm over a low heat to dissolve the sugar and melt the butter, stirring occasionally.
When the sugar has dissolved, put a sugar thermometer in the mixture, making sure the end is completely covered by the syrup – if it’s not, transfer the mixture to a smaller pan that’s still large enough for the syrup to bubble. Turn up the heat to medium-high and bring the syrup to the boil, stirring occasionally to stop it catching. When the thermometer reaches 116C – or ‘soft ball’ stage, remove the pan from the heat.
Leave the mixture to stand, undisturbed, for 5 mins, until the temperature drops to 110C, then stir in the vanilla bean paste, mixed spice, mixed dried fruit and peel, the orange zest and a good pinch of salt.
Remove the thermometer, then vigorously beat the mixture with a wooden spoon, checking the temperature every minute or so until it drops again to about 60C. By this time, the mixture will be really thick and have lost its glossy shine. Take the thermometer out and continue beating the mixture for a few more minutes. This part is crucial as it helps create small sugar crystals that give the fudge its smooth, creamy texture.
Quickly pour the fudge mixture into the prepared tin and smooth the surface using a spatula. Leave to cool overnight at room temperature – don’t put it in the fridge, as it will become sticky and won’t set properly. Cut into 36 bite-sized pieces. Will keep in an airtight container at room temperature for up to two months.