1. Line a 9×13-inch pan with parchment paper, leaving an overhang on two sides. Lightly grease the parchment paper and a silicone spatula.

2. Place the crisp rice cereal in a large bowl. Measure the mini marshmallows and reserve 2 cups for folding into the mixture later.

3. Melt the salted butter in a large, heavy saucepan over low heat without allowing it to brown.

4. Add the remaining marshmallows. Stir slowly over low heat for 3 to 4 minutes, just until the mixture is smooth. Remove the saucepan from the heat as soon as the final lumps disappear.

5. Stir in the vanilla extract and a small amount of orange gel food coloring. Add more coloring gradually until the desired shade is reached.

6. Immediately add the cereal and fold until it is evenly coated. Fold in the reserved marshmallows during the final few turns so they soften slightly but remain partly visible.

7. Transfer the mixture to the prepared pan. Use the greased spatula or a sheet of parchment paper to guide it into the corners and press it gently into an even layer without compacting it.

8. Add the Halloween sprinkles and candy eyes while the surface is still tacky. Let the treats cool at room temperature for approximately 45 minutes.

9. Lift the slab from the pan and cut it into 15 rectangles with a lightly greased knife. Drizzle the treats with melted semisweet chocolate or dip one corner of each bar. Let the chocolate set before serving or stacking.