He is making fun of her baking skills. מטקות is the name of the game, but is also how the instruments that are used in the game are called. מטקה אחת, שתי מטקות. Basically, he is saying that she puts these instruments in a cake.
The insistence on 'have' over 'did' in this sentence is irritating as either would do in English and it seems to me that either one could be accepted.