Slowcooker Ranch Butter Mushrooms: An easy appetizer for a party or gathering. No one will ever believe there are only three ingredients after experiencing the flavor punch. I leave the mushrooms whole rather than slicing them. Leftover butter is good for brushing on steaks or as a base for white wine sauces. Just mushrooms, 1 pkg Ranch dressing mix, and 1/2 c butter melted. Throw it in the crockpot for 3-4 hours on low. Yum yum yum!