Preheat the oven to 180° Celsius

Line a rectangular baking tin with baking paper

Melt the butter and the chocolate over a bain-marie and mix until smooth

In a separate bowl sift together the cocoa powder, baking powder and fructose

Add the starter and mix in

Add the marshmallows and mix

Add the melted chocolate and stir well

Add the eggs and mix in until you have a silky consistency

Pour the mix into the baking tray and bake for 20 minutes

The brownies must still be gooey inside when you take them out the oven

Cool in the tray before removing and cutting into squares