Name: Brownie Bomb Bars
Prep time: 20 min
Cook time: 45 min
Total time: 2 min
Ingredients: 1 box Double chocolate premium brownie mix (18 oz, use as directed); 1 large Egg (room temperature); 1/3 cup Vegetable oil (or any neutral oil); 1/4 cup Water (room temperature); 1 jar Jet-puffed marshmallow creme (7 oz, spreadable); 1/3 to 1/2 cup Sweetened flaked coconut (optional to taste); 2 cups Milk chocolate chips (for melting); 1 cup Chunky peanut butter (creamy or chunky works); 3 1/2 cups Cocoa krispies cereal (or similar chocolate puffed rice cereal)

Jump to Recipe

Creamy, crunchy, and unapologetically decadent — Brownie Bomb Bars are the kind of dessert that makes everyone at the table pause mid-conversation and reach for another square. This layered treat starts with a rich, fudgy brownie base, gets a gooey marshmallow-coconut middle, and finishes with a crunchy chocolate-peanut butter-cereal topping that snaps in every bite. Fun fact: layered bars like this were popularized during potluck eras when efficiency and crowd-pleasing flavors were everything.

This recipe is special because it’s simple to assemble, requires mostly pantry staples, and delivers bakery-level flavor without the fuss. It’s quick enough for a weekend bake and family-friendly enough to involve the kids in simple tasks. If you love inventive brownies, you might also enjoy our playful take on stuffed brownie bites like Chocolate Chip Cookie Dough Brownie Bombs, which share a similar over-the-top spirit. Ready your spatula and a crowd — these bars disappear fast!

What is Brownie Bomb Bars?

Ever wonder why they’re called Brownie Bomb Bars? Is it because they explode with flavor, or because they look like little dessert TNT? Maybe both. The name is a cheeky nod to how one modest brownie slab can send your taste buds into a fireworks display of chocolate, marshmallow, peanut butter, and crunch. Some say “the way to a man’s heart is through his stomach.” but I’ll argue it’s through a tray of these bars — and no one’s ever turned them down.

A playful anecdote: the first time I brought these to a family gathering someone whispered, “Are these safe?” — and by the end of the night, the pan was suspiciously empty. Curious? Make a batch and see how quickly they “go off”.

Why You’ll Love This

Big flavor payoff: The standout is the contrast — dense, fudgy brownie with a pillowy marshmallow layer and a crunchy chocolate-peanut butter topping. Textures and flavors play off each other beautifully.
Wallet-friendly baking: Using a boxed brownie mix as the base keeps costs low and prep quick, while pantry ingredients like marshmallow creme, coconut, and cereal bulk the recipe affordably for big groups.
Crowd-pleasing appeal: Kids love the crunch and adults appreciate the nostalgic combination of chocolate and peanut butter. These bars are perfect for bake sales, family dinners, or casual parties.

If you like classic brownies or our other layered treats, these will feel familiar but more playful and over-the-top — a fun follow-up to simpler bar recipes like the brownie bombs on the site. Make them for a crowd or keep them in the fridge for an indulgent weekday treat. Go on — treat yourself.

How to Make:

Quick Overview

This recipe is easy and forgiving. The prep is mostly mixing and spreading; the standout element is the crunchy chocolate-peanut butter-cereal topping that sets into a satisfyingly firm layer after refrigeration. Prep time is about 20 minutes, bake time 35 to 45 minutes, and chilling time at least 2 hours. Total active time is low and the payoff is huge.

Ingredients

1 (18 oz) box double chocolate premium brownie mix with chocolate chips — for the base (use the mix as directed below)
1 large egg — room temperature for easier mixing
1/3 cup vegetable oil — or any neutral oil
1/4 cup water — room temperature
1 (7 oz) jar jet-puffed marshmallow creme — spreadable marshmallow layer
1/3 to 1/2 cup sweetened flaked coconut — sprinkle over marshmallow (optional to taste)
2 cups milk chocolate chips — for the topping, melted
1 cup chunky peanut butter — creamy or chunky works; chunky adds texture
3 1/2 cups cocoa krispies cereal — or similar chocolate puffed rice cereal, stirred into melted chocolate mixture

Directions

Preheat your oven to 325°F (163°C). Lightly grease a 13×9-inch baking pan and set it aside. Greasing well helps with removing the bars later.
In a medium bowl, add the brownie mix, 1 large egg, 1/3 cup vegetable oil, and 1/4 cup water. Mix with a spatula or mixer until fully combined and smooth; scrape the sides so there are no dry streaks.
Spread the brownie batter evenly into the prepared 13×9-inch pan using an offset spatula or the back of a spoon to get a flat, consistent layer.
Bake in the preheated oven for 35 to 45 minutes. Start checking at 35 minutes — a toothpick inserted in the center should come out with a few moist crumbs but not wet batter. Don’t overbake; you want a fudgy center.
Remove the pan from the oven and let it cool completely on a wire rack. Cooling fully is important so the marshmallow layer doesn’t melt.
Once cooled, spread the entire jar of marshmallow creme evenly over the brownie layer. If it’s thick, warm the jar briefly (5–10 seconds) in the microwave to make spreading easier. Sprinkle 1/3 to 1/2 cup sweetened flaked coconut over the marshmallow layer.
In a microwave-safe bowl, combine 2 cups milk chocolate chips and 1 cup chunky peanut butter. Microwave in 1-minute intervals, stirring between each, until fully melted and smooth. Be careful not to scorch the chocolate.
Stir 3 1/2 cups cocoa krispies cereal into the melted chocolate-peanut butter mixture until the cereal is evenly coated.
Immediately spread the chocolate-peanut butter-cereal mixture evenly over the marshmallow-coconut layer, pressing lightly so it adheres.
Cover the pan with plastic wrap or foil and refrigerate for at least 2 hours to set. For cleaner slicing, chill longer.
Once set, remove from the refrigerator and cut into bars. Serve chilled or at cool room temperature.

Brownie Bomb Bars

What to Serve With

Cold milk or iced coffee — the classic pairing for a rich, chocolate bar.
Fresh berries or a citrus salad — the acidity brightens the richness.
A scoop of vanilla ice cream — warm or chilled bars with vanilla is heavenly.
Whipped cream and a drizzle of caramel or chocolate sauce — for an extra-decadent dessert plate.
For a party, plate with mixed nuts and salted pretzels to balance sweetness with savory crunch.

Top Tips for Perfecting

Use room-temperature egg and water for smoother batter.
Don’t overbake the brownie base — it should be fudgy, not cake-like. Check at 35 minutes.
If marshmallow creme is difficult to spread, microwave the jar for 8–10 seconds to loosen it.
Substitute almond butter or sunflower seed butter for peanut butter to accommodate allergies.
For extra texture, fold a handful of chopped nuts into the cereal topping before spreading.
Common mistake: assembling while the brownie is still warm — this will melt the marshmallow and create a mess. Cool completely first.

Storing and Reheating Tips

Refrigeration: Store in an airtight container in the refrigerator for up to 5 days. Chilling keeps the chocolate-peanut butter topping firm.
Freezing: You can freeze individual bars wrapped in parchment and foil for up to 2 months. Thaw overnight in the refrigerator before serving.
Serving from chilled: Let bars sit at room temperature for 10–15 minutes for easier eating, or serve cold for a firmer bite.
Reheating: If you prefer a slightly softer texture, microwave a single bar for 10–12 seconds on medium power; avoid overheating to prevent melting the marshmallow and chocolate.

FAQs

Can I make these without a boxed brownie mix?
Yes. Substitute with your favorite homemade brownie batter; follow the same steps for baking time but check doneness earlier as homemade recipes vary.

Can I use smooth peanut butter instead of chunky?
Absolutely. Smooth gives a silkier topping while chunky adds extra crunch. Both work well.

Is the coconut necessary?
No — the coconut adds a toasted, chewy contrast but you can omit or replace it with chopped nuts if preferred.

Can I make these nut-free?
Yes. Replace the peanut butter with sunflower seed butter or a nut-free spread and ensure the chocolate chips are processed in a nut-free facility if needed.

How do I get clean slices when cutting?
Chill thoroughly, then use a large sharp knife warmed under hot water and dried between cuts for cleaner edges.

Conclusion

Brownie Bomb Bars are a simple, attention-grabbing dessert that transforms pantry ingredients into a show-stopping tray bake. They’re easy enough for a weeknight treat but impressive enough for gatherings, with layers that bring contrast in texture and flavor. Try them chilled for the crispiest topping, or let them sit a few minutes at room temperature for a gooier chew. For another fun take on brownie bars and regional variations, see this delightful version: Kentucky Brownie BOMB Bars! – My Incredible Recipes. Share a pan with family or friends — I promise they’ll ask for the recipe.