8 Tbsp unsalted butter, plus more to grease pan
16 oz mini marshmallows, divided into 6 cups and 2 cups
1 tsp vanilla extract
1/2 tsp salt
7 cups crispy rice cereal

Butter and line a 9×9 baking dish with parchment paper (you can use a 9×13 but the squares won’t be as thick).

In a large pot or dutch oven, melt butter over medium/low heat. Add 6 cups marshmallows and stir just until completely melted (don’t overcook or the mixture will harden).

Remove the pan from the heat and immediately stir in vanilla and salt. Working quickly stir in the cereal then fold in the remaining 2 cups marshmallows until well coated and the added marshmallows just start to melt but are still chunky.

Immediately transfer the mixture to the prepared pan, place a piece of plastic wrap or parchment paper over the top to prevent sticking and lightly pressing it evenly into the pan.

Set aside to cool completely to room temperature (about 1 hour), then slice into squares and enjoy.

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As an alternative, prepare the basic recipe using other cereals: Cocoa Puffs, Cocoa Krispies, Froot Loops, etc.

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To make it more decorative, you can create a cake by stacking the squares in a pyramid.

You can also make sandwiches with a glaze center:
1 c. semisweet chocolate chips
1/2 c cream

Prepare glaze by melting and stirring chips and cream over medium heat, beating until smooth. Pour over half the squares. Top with the remaining squares.

Another approach:
Chocolate/Peanut Butter Treats

3 T butter
1 10-oz pkg chocolate marshmallows
1 c peanut butter
1 t vanilla
1 t chocolate extract
6 c cocoa krispies
1 2-oz block vanilla candy coating

Grease 9×13 baking dish.
Melt butter, add marshmallows, stir until melted. Remove from heat, stir in 1/2 c peanut butter, vanilla and chocolate extract.  Add cereal, stir to combine. Grease hands and press into prepared pan. Cool 1 hour. Cut into shapes.
In a small bowl, microwave 1/2 c peanut butter for 20 seconds, til liquid.
In separate bowl, melt candy coating at 30-second intervals til liquid. Whisk together peanut butter and coating. Cool 5 minutes. Place in pastry bag and drizzle over treats. Allow to dry in parchment paper.