Disappearing Marshmallow Brownies What Went Wrong With My Rocky Road Chocolate Muffins?

What went wrong with my Rocky Road chocolate muffins? - disappearing marshmallow brownies

Hello boys
I bought a cookbook today Muffins (negotiations as a whole) and decided to try the Rocky Road chocolate cake.
I'm used to, but not muffins cupcakes, but the recipe was not difficult.
I constituents at:
225g flour
55g cocoa powder
1 teaspoon baking powder
Pinch of salt
115g caster sugar
100 white chocolate chips
50g white marshmallows, halved
2 medium eggs
250 ml milk
6 tbsp sunflower oil

Now, why I am here not a happy bunny:
- They are in bad taste! Seriously marshmallows have completely disappeared and the taste is very smooth
- He says, for 20 minutes in the preheated oven bake at 200C. I opened the envelope after 20 minutes and immediately went flat, firm, but not burn to the ground!
- Also, I do not know if it is large, but that is a powder unsweetened cocoa

Do you know what went wrong? Is there a Rocky Road chocolate muffin recipe?

I thought it was a good cook, but now I feel reallyFool!