Eileen's FAMOUS rice krispy treats

I dream about Eileen's rice krispy treats.  They are soft, and gooey and irresistible.  We've all had stale, crunchy, dry rice krispy treats but hers are amazing every time.  Turns out her secret is more butter and marshmallows than the original recipe.  Go figure!  Mark and I shared about a 3x3 spare of this pan with the kids and ate the rest in 2 days.

4 tablespoons butter
1 package miniature Kraft marshmallows (don't use generic)
6 cups Rice Krispies cereal (generic ok)

In microwave-safe bowl heat butter and marshmallows on HIGH for 3 minutes, stirring after 90 seconds. (Microwave cooking time may vary) Stir until smooth. Add rice krispies and stir until well coated. Using buttered spatula or wax paper evenly press mixture into 13 x 9 x 2-inch pan coated with cooking spray. Cool. Cut into 2-inch squares.