Line a 9-by-13-inch baking pan with parchment paper, leaving a little overhang on the sides. This makes it so easy to lift everything out later without any stuck bits. Trust me on this — I learned the hard way by scrubbing a pan for 20 minutes once.

Melt the butter and marshmallows together in a large pot over medium heat, stirring constantly. You'll need about 3 to 4 minutes until everything combines smoothly. Add the vanilla extract and salt, then stir for another 30 seconds.

Divide the marshmallow mixture into 3 equal bowls right away — one stays plain, one gets red food coloring, and one gets blue. Stir each bowl until the color is totally even and vibrant. I always work quickly here because the mixture starts setting as it cools.

Add 1 and 1/3 cups cereal to each colored marshmallow mixture, folding gently but thoroughly. Work fast so the cereal doesn't start sticking together weird. If it feels too thick, you're good — that's actually perfect for spreading.

Press the white layer into your prepared pan first, creating an even 1/2-inch thickness. Then layer the red mixture on top, pressing gently. Finish with the blue layer, making sure each section stays distinct and visible.

Sprinkle matching sanding sugar over each layer while everything's still warm and a little sticky. The sugar adheres best when the treats are hot, so don't wait. I press the sugar down gently with my fingers to help it stick.

Let the whole pan cool at room temperature for at least 2 hours — don't skip this step. Cut into 12 squares with a sharp knife dipped in water. The water prevents sticking and gives you clean edges.

For the chocolate drizzle, combine chocolate chips, milk, and honey in a small microwave-safe bowl. Heat for 30 to 45 seconds, stir, then heat again for 15 seconds if needed. Drizzle lightly over the cooled squares using a fork or squeeze bottle.