In large bowl melt butter in microwave just until melted. Add marshmallows, stir to coat marshmallows in butter, then microwave until melted, stirring occasionally. This should only take a couple of minutes.
Stir in vanilla.
Stir in Rice Krispies.
Pour into buttered pan and press mixture firmly with buttered hands.
Place in refrigerator to chill.
In saucepan, melt caramels and water on low heat, stirring frequently. (careful not to burn).
Remove from heat, stir in ½ cup peanut butter. Blend completely.
Pour over Rice Krispies, and spread to an even layer.
Put back into refrigerator.
In saucepan over low heat, melt chocolate.
When melted, stir in ¼ cup peanut butter. Combine well.
Pour chocolate over caramel layer spreading to edges in even layer.
Refrigerate for 1 hour or until chocolate is firm.