I'm always losing the recipe for these, so I decided to put it here.
1-12 oz. box of rice krispie cereal
1-16 oz. bag of jet-puffed mini marshmallows
1 stick of butter
1 tsp. of vanilla
Melt butter in large pot over low heat. It's important to do it slowly and not let the butter get browned. Stir in vanilla. Stir in marshmallows and continue cooking over low heat until the marshmallows are melted and the mixture has reached a smooth consistency. Stir in cereal. Pour into a buttered pan. You can use a 13 x 9 baking dish for thicker treats or use a rimmed cookie sheet for thinner treats. Using wet hands, so the mixture will not stick, press into the pan evenly. Let cool completely. Cut into desired size of bars.