Line a 9x13-inch baking dish with parchment paper or lightly grease it.

In a large saucepan over low heat, melt the butter and add mini marshmallows, stirring until smooth.

Stir in lemon zest, lemon juice, vanilla extract, and a pinch of salt.

Remove from heat and fold in crispy rice cereal until evenly coated.

Press mixture into prepared baking dish using a buttered spatula.

Optional: whisk powdered sugar with lemon juice and drizzle over treats.

Let cool completely for about 1 hour, then slice into squares.

Serve immediately or store in an airtight container.