These Glow in the Dark Rice Krispies Treats are spookily fun and surprisingly simple. With a classic gooey base and a black light reactive glaze, they turn any Halloween party into a neon dessert moment. They do not glow in pitch dark, but they shine brilliantly under a UV black light.
Why You’ll Love This Glow in the Dark Rice Krispies Treats
- Party showstopper that actually glows under black light
- Familiar, buttery marshmallow flavor with a festive twist
- Kid-friendly to make and perfect for classroom or trunk-or-treat
- Easy pantry ingredients with simple glow add-ins
- Make ahead and slice when you are ready to serve
Glow in the Dark Rice Krispies Treats Ingredients & Substitutions
- 6 cups crispy rice cereal
- 4 tablespoons unsalted butter
- 10 ounces mini marshmallows, plus 1 cup extra to stir in at the end
- 1 teaspoon vanilla extract
- 1/4 teaspoon kosher salt
- Nonstick spray or a little butter for the pan
- Optional mix-ins: 1/2 cup neon green or orange sprinkles
Black light glow glaze:
- 1 cup powdered sugar
- 3 to 4 tablespoons tonic water for glow under UV
- 1 teaspoon light corn syrup or glycerin for shine and set
- Neon gel food coloring, preferably yellow or electric green
- Optional boost: 1/8 to 1/4 teaspoon riboflavin powder (vitamin B2), finely ground, for extra fluorescence
Substitutions:
- Dairy free: use vegan butter
- Vegan: use vegan marshmallows and plant butter
- Gluten free: use certified gluten free crispy rice cereal
- No tonic water: use just neon gel coloring and a splash of milk or water in the glaze. It will still pop under UV, though a little less.
Step-by-Step Instructions to Make Glow in the Dark Rice Krispies Treats
Prep the pan
Line an 8 or 9 inch square pan with parchment, leaving overhang for easy lifting. Lightly grease parchment and a spatula with butter or spray.
Melt butter and marshmallows
In a large pot over low heat, melt butter. Add 10 ounces mini marshmallows and salt. Stir slowly until fully melted and glossy. Take off heat and stir in vanilla.
Fold in cereal
Add cereal and fold gently until evenly coated. If you like extra pockets of marshmallow, fold in the remaining 1 cup mini marshmallows now.
Press and set
Scrape mixture into the pan. Use the greased spatula or lightly buttered hands to press into an even layer without packing too firmly. Let cool 20 to 30 minutes until set.
Make the black light glow glaze
Whisk powdered sugar, 3 tablespoons tonic water, and corn syrup until smooth and thick but pourable. Add a tiny amount of neon gel coloring. For extra glow, whisk in riboflavin powder a pinch at a time to taste. If too thick, add the remaining tonic water by teaspoons.
Glaze and decorate
Lift treats from the pan and transfer to a board. Drizzle glaze in zigzags or spread a thin layer. Add neon sprinkles while the glaze is tacky. Let set 15 to 20 minutes.
Test the glow
Flip on a UV black light. The glaze will fluoresce bright yellow-green. Adjust with a little more neon color or a tiny pinch of riboflavin if you want stronger glow.
Tips for Success
- Low and slow heat keeps marshmallows silky and prevents tough treats
- Do not overpack the mixture in the pan or the bars will be dense
- Grease your spatula and hands to keep things mess free
- Use fresh marshmallows; stale marshmallows melt into sticky strings
- Black light matters: UV-A party bulbs work best for a bright glow
Variations of Glow in the Dark Rice Krispies Treats
- Monster mash: stir in candy eyeballs and chocolate chip pupils after pressing
- Peanut butter twist: add 1/3 cup creamy peanut butter with the melted marshmallow
- Fruity crunch: swap 2 cups crispy rice for fruity cereal for color
- Chocolate drizzle: finish with white chocolate lines before the glow glaze
- Party shapes: press into a parchment lined sheet and cut with pumpkin or ghost cookie cutters
Serving Suggestions: What to Pair with Glow in the Dark Rice Krispies Treats
- Pitcher of apple cider or hot cocoa for cozy contrast
- Neon snack board with gummy worms, pretzels, and clementine pumpkins
- Serve on white platters so the colors pop under UV
- Set up a black light dessert zone for the big reveal
Storage & Reheating Instructions
- Store: Airtight container at room temperature up to 3 days
- Soften: If a bar feels firm, microwave 5 to 8 seconds
- Freeze: Wrap bars individually in parchment, then bag for up to 1 month. Thaw at room temperature 20 minutes
- Avoid refrigeration, which can dry out marshmallows
Memories Made Around the Table
We made these for a neighborhood costume party, and I will never forget the kids squealing when the lights clicked off and the black light flicked on. Every slice lit up like a friendly little lantern.
FAQs
Do these treats glow in complete darkness? They glow under a UV black light. In regular darkness without UV, they will not glow.
Is the glow safe to eat? Yes. Tonic water and riboflavin are common food-safe ingredients. If you are sensitive to quinine, skip tonic water and use neon gel coloring under UV.
Can I make them ahead? Yes. Make up to 24 hours in advance. Glaze the day of serving for the brightest shine.
My treats turned hard. What happened? Likely too much heat or pressing. Melt marshmallows over low heat and press gently. A brief 5 to 8 second microwave softens a firm bar.
Can I skip the glaze and still get glow? The glaze gives the strongest effect. Neon gel food coloring mixed into the marshmallow base will show some glow under UV, but the glaze concentrates it on the surface.
Final Thoughts
These Glow in the Dark Rice Krispies Treats are easy to love and even easier to share. Prep the UV light, gather your ghouls, and let this cheerful dessert steal the show.
Glow in the Dark Rice Krispies Treats (Black Light!)
Equipment
- 1 Large Pot
- 1 8- or 9-inch square pan
- 1 Parchment Paper
- 1 Rubber spatula greased
- 1 Mixing Bowl for glaze
- 1 Whisk
- 1 UV black light for the glow effect
Ingredients
Rice Krispies Treats
- 4 tbsp unsalted butter
- 10 oz mini marshmallows
- 1 tsp vanilla extract
- 0.25 tsp kosher salt
- 6 cup crispy rice cereal
- 1 cup mini marshmallows stir in at the end (optional)
- nonstick spray or butter for the pan
Optional Mix-Ins
- 0.5 cup neon green or orange sprinkles
Black Light Glow Glaze
- 1 cup powdered sugar
- 3 tbsp tonic water 3 to 4 tbsp total, as needed
- 1 tsp light corn syrup or glycerin for shine and set
- neon gel food coloring yellow or electric green
- 0.125 tsp riboflavin (vitamin B2) powder up to 1/4 tsp, optional, finely ground
Instructions
Make the treats
- Line an 8 or 9 inch square pan with parchment, leaving overhang for easy lifting. Lightly grease the parchment and a spatula with butter or spray.
- In a large pot over low heat, melt the butter. Add 10 ounces mini marshmallows and the salt. Stir slowly until fully melted and glossy. Remove from heat and stir in the vanilla.
- Add the crispy rice cereal and fold gently until evenly coated. If you like extra pockets of marshmallow, fold in the remaining 1 cup mini marshmallows now.
- Scrape the mixture into the prepared pan. Use the greased spatula or lightly buttered hands to press into an even layer without packing too firmly. Let cool 20 to 30 minutes until set.
Glaze and glow
- Whisk the powdered sugar, 3 tablespoons tonic water, and corn syrup until smooth and thick but pourable. Tint with a tiny amount of neon gel coloring. For extra glow, whisk in riboflavin powder a pinch at a time. If too thick, add more tonic water by teaspoons.
- Lift the slab from the pan and transfer to a board. Drizzle glaze in zigzags or spread a thin layer. Add neon sprinkles while the glaze is tacky. Let set 15 to 20 minutes.
- Flip on a UV black light—the glaze will fluoresce bright yellow-green. Adjust with a touch more neon color or a tiny pinch of riboflavin if you want stronger glow.