Melt your 4 Tbsp of butter
Add 1 10oz Bag of Marshmallows
Stir until mixture is smooth
Add in 5 cups Rice Krispie cereal
Add in 1 Cup Fruity Pebbles
Add in 1/2 of the remaining 10oz bag
Stir until combined
Pour mixture into greased dish
Allow to cool and cut into serving-sized squares
Or eat them while they're still warm!