The recipe I use calls for 1 stick of butter and 1 pkg of dressing mix per 16 oz. of mushrooms. I use a medium size crock pot. Basically, 2 lbs of mushrooms fills it to the top. It looks like a lot but don't worry the mushrooms will shrink down. Melt the butter in a bowl in the microwave. 2 sticks of butter only takes about 60 seconds. Add the dressing mix to the melted butter and stir. Pour over the mushrooms and set crock pot on low. Cook for about 4 hrs. About half way through, as the mushrooms cook down and everything is hot, stir them gently and bring up some of the melted butter from the bottom and pour over the top.
You can serve them with rice or Teriyaki noodles.
Load the crock pot with mushrooms.
Ranch dressing mix and real butter.
Melt the butter and stir in dressing mix.
Pour melted butter mix over the mushrooms.
Cooking in the buttery mix. Almost done.