Begin by preheating the oven to 350°F (175C/155C Fan) and lining a 12-hole muffin pan.
Place the raisins, bourbon and orange juice in a small saucepan and bring to a boil over a medium heat. Once boiled, allow to cook for about 3 minutes before removing from the heat and setting aside.
In a separate saucepan, place the butter and treacle. Stir together over a medium heat and bring to a boil. Once boiled, remove from the heat and add the sour cream, vanilla and orange zest.
In a large mixing bowl, sift together the flour, baking soda, ginger, cinnamon, cloves and salt.
Pour the treacle mixture into the mixing bowl with the flour and whisk together. Then add the raisins along with the soaking liquid and stir to combine.
Spoon the mixture evenly into the muffin pan and place in the centre of the preheated oven to bake for about 30 minutes. Check for doneness by using a skewer inserted into the middle of a central muffin. Once this comes out clean, the muffins are done.
When ready, remove the pan from the oven and transfer the muffins to a wire rack to cool.
Serve as they are or frost with buttercream.