Make sure you have all of your ingredients and supplies.
Use butter or non-stick cooking spray to pre-grease your pans and spatula.
First melt your butter and marshmallows together. This can be done on the stove or in the microwave. Stove instructions are in the post above, microwave instructions are below.
Toss 8 tbs of butter in a bowl with 32 oz of marshmallows.
Toss the bowl into the microwave and heat for 30 - 60 seconds
Stir the marshmallows and butter together, then heat again for 30 seconds.
Heat and stir for 30 second intrervals until marshmallows are completely melted.
Fold in 12 cups of rice krispie cereal with your marshmallows.
Transfer treat mixture into your three pans and gently press it down into each pan.
Allow around 30 minutes for treats to cool.
Flip your first pan over onto a plate so that treats come out of pan, ice top and sides.
Then, flip next pan over onto first treat and ice the second layer.
Do the same for the third layer and ensure all layers are iced.
Add sprinkles all over cake.