Place 375ml (1 1/2 cups) water and sweetener in a saucepan. Gently heat and mix with a whisk until all the sweetener is dissolved and the water is warm. Do not boil. Remember to add sweetener to your taste. You may wish to add more sweetener to your liking before going onto step 2.
Place 125ml (1/2 cup) of hot water into a heatproof jug and sprinkle the gelatine into it. Stir with a whisk until all the gelatine is dissolved.
Add the dissolved gelatine to the sweetened warm water in the saucepan and mix well. Allow to cool.
Divide the mixture into 4 bowls, large enough to use an electric hand mixer.
In each bowl add the flavouring and any colouring you wish to add.
Whisk the sugar-free marshmallow mixture until it is light and fluffy and almost spongy. Pour into a lined dish to set. Repeat with all flavours.
Place in the fridge, then cut into squares or shapes with a sharp knife dipped in warm water to stop it from sticking to the marshmallows.
The nutrition panel shows per 100g of sugar-free marshmallows.