Begin by preparing a 9×13-inch baking pan. Line it with parchment paper and lightly grease the surface with nonstick spray, ensuring an easy release later.

In a large pot over medium heat, melt the butter. Once it’s fully melted, add in the mini marshmallows. Stir continuously until the marshmallows are completely dissolved and blended with the butter.

Remove the pot from the heat and quickly mix in the vanilla extract and a pinch of salt. Next, gently fold in the crispy rice cereal, ensuring that every piece is thoroughly coated with the gooey marshmallow mixture.

Transfer the combined mixture into the prepared pan. Using a lightly greased silicone spatula, carefully spread the mixture to fill the pan evenly. With the back of a flat spatula, gently press down on the mixture to compact it slightly, being cautious not to pack it too tightly.

Allow the treats to set at room temperature for at least one hour or up to a full day. If you need to leave them out for more than a few hours, cover them tightly to keep them fresh.

Once set, lift the entire block of treats out of the pan using the parchment paper edges. Cut into squares for serving.

Store any leftovers in an airtight container at room temperature for up to three days, placing parchment or wax paper between layers to prevent sticking.