- STEP 1
Heat the oven to 190C/375F/Gas 5. Line a 30cm/12in square tin with baking parchment.
- STEP 2
Gently melt the butter and the chocolate together.
- STEP 3
Mix the cocoa, flour and sugar and mix into the butter and chocolate. Mix in the beaten eggs then fold in the marshmallows.
- STEP 4
Pour the brownie mixture into the tin and bake in the oven until the surface has set but still feels squidgy underneath. This will take about 20 -30 minutes. Allow to cool in the tin before slicing.