Preheat your oven to 175 Celsius / 350 Fahrenheit.
In a food processor or with a blender, mix the butter, granulated sweetener and sugar free syrup.
Add the eggs and blend.
Add the dry ingredients and spices and blend until smooth.
Fill into 8 paper or silicone cups (I used silicone cups which I greased with butter, just in case) and place in a muffin/cupcake pan. My batter was quite thick - it softens as it heats.
Bake ca 20 minutes.
To prepare the frosting, heat the cream with the fibre syrup in a small pot and let it bubble over a medium heat until it reduces - around 5-10 minutes.
Stir in the brown sugar replacement, add a pinch of salt and let the mixture cool. Keep stirring from time to time.
Once the caramel is only lukewarm, whisk it into the softened butter.
Let the cupcakes cool completely before you decorate with the caramel frosting.
I had the oven on 190 Celsius in the beginning, that's why my cupcakes browned a little too much on the top. I reduced the heat to 175 Celsius as soon as I noticed. If you set your oven to 175/350 Fahrenheit, yours should come out perfectly.