In a microwaveable bowl, warm 4 cups marshmallows and butter in the microwave about 1½ minutes, stirring in 30 second intervals until the marshmallows are fully melted. Stir in pudding mix and water and mix until well combined.
Stir cereal, remaining 2 C of marshmallows and almonds into the marshmallow mixture, folding until all the cereal is coated.
Transfer into greased baking dish, pressing down lightly into pan until level. Refrigerate until chilled and slice into squares.