- Butter, for greasing
- 450 g pack Madeira cake mix
- 2 medium free-range eggs
- 150 ml semi-skimmed milk
- 3 tbsp cocoa
- 400 g marshmallows
Preheat the oven to 180ºC, fan 160ºC, gas 4. Use the butter to grease a non-stick 20cm x 25cm rectangular cake tin. Tip the cake mix into a large bowl and add the eggs, milk and cocoa. Using an electric hand-held whisk, beat together for 2 minutes.
Spoon the mixture into the prepared cake tin. Bake for 13-15 minutes until cooked through. Remove from the oven and preheat the grill to medium-high.
Scatter the marshmallows evenly over the top of the cake, then place under the grill for 1-2 minutes until they are lightly toasted and beginning to melt. Allow the traybake to cool for a few minutes, then cut into bars to serve.