Halloween Brownies Recipe

These Halloween brownies are fudgy cocoa brownies baked in one 9×13 pan, cut into 12 squares, and decorated with a piped chocolate spiderweb, a candy eyeball and a gummy worm. Prep takes about 20 minutes, and the pan bakes for 28 to 32 minutes at 350°F.

The trick is the order. Cut the cooled slab first, then decorate each square on its own, so the knife never drags through a finished web. A teaspoon of oil in the melted chips keeps the lines soft enough to grab the candy.

Spiderweb Brownies by the Numbers

• Pan: 9×13 inch, lined with parchment that hangs over two sides
• Yield: 12 squares, about 3 by 3¼ inches each
• Oven: 350°F (175°C) for 28 to 32 minutes
• Brownie base: 1 cup butter, 2 cups sugar, 1 cup cocoa powder, 4 eggs, 1 cup flour
• Decorating: ½ cup semisweet chips melted with 1 teaspoon vegetable oil, 12 candy eyeballs, 12 gummy worms
• Equipment: one big bowl, a spatula and a zip top bag; no mixer
• Keeps: 3 days at room temperature, 5 days in the fridge, 2 months frozen

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A Cocoa Batter Built to Carry Candy

This base uses cocoa powder only, no melted chocolate bars. That matters here. Cocoa brownies bake with a firm, flat top and clean edges, which is what you want under piped chocolate. Brownies made with a lot of melted chocolate come out softer and gooier, so the squares slump and the candy sinks. My cocoa powder brownies go deeper into the cocoa-only method if you are curious.

Melt the butter fully, then stir in the sugar and cocoa. The hot butter dissolves some of the sugar and wakes up the cocoa, and the bowl starts to smell like hot chocolate. Add the vanilla, then the eggs one at a time. After the last egg the batter should look thick and shiny. That shine is what bakes into a thin, crackly top.

Sift the flour, salt and baking powder over the bowl and fold with a spatula just until the dry streaks disappear. Keep stirring past that point and the brownies turn cakey, with tough edges.

The card is written for natural cocoa. Dutch process cocoa works as well, because baking powder carries its own acid. Expect darker brownies with a slightly milder taste.

When to Pull the Pan From the Oven

Spread the batter into the lined pan and bake at 350°F. Start checking at 28 minutes. A toothpick in the center should come out with a few moist crumbs, not wet batter and not clean. The edges look set and pull away from the parchment a little, while the middle still looks slightly soft.

A clean toothpick means you went too far. Overbaked squares crumble when you cut them, and decorating a crumbly brownie is no fun. They keep firming as they cool, so a minute early is the safer side.

Let the brownies cool completely in the pan. Warm brownies melt piped chocolate into smears, and the eyeballs slide off. Touch the bottom of the pan. If it still feels warm, wait, or slide the pan into the fridge for 15 minutes.

Cut First, Decorate Second

Lift the cooled slab out by the parchment and set it on a board. Cut 3 rows by 4 for 12 squares of about 3 by 3¼ inches. A long knife pressed straight down gives cleaner sides than sawing back and forth. Wipe the blade with a damp paper towel after every cut, or the crumbs from one cut smear into the next.

Spread the squares out on a parchment lined tray with a little room between them. Now every brownie gets decorated on its own, and each web arrives at the table whole.

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Drawing a Chocolate Spiderweb With a Sandwich Bag

Put the ½ cup chocolate chips and 1 teaspoon vegetable oil in a microwave safe bowl. Heat in 20 second bursts and stir after each one. Stop while a few small lumps remain and stir until they melt in the leftover heat. Chips that get too hot turn thick and dull, and then nothing flows out of the bag.

Spoon the chocolate into one corner of a zip top bag and snip off the very tip, about 2 millimeters. A bigger hole gives fat lines that blur together. Pipe one test line on the parchment before you start on a brownie.

For a web people recognize at a glance, pipe 3 or 4 rings, one inside the other, on a square. Then drag a toothpick from the center out to the edge 6 to 8 times, like the spokes of a wheel. Each pull stretches the rings into points. You can also pipe the spokes first and join them with small sagging curves. Wobbly lines are fine. Real spiderwebs are not tidy either.

Decorating with kids? Let them pipe a few practice webs on parchment to feel how hard to squeeze, then hand them their own squares.

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Where the Eyeball and Gummy Worm Go

Work one square at a time. The chocolate stays soft for only a couple of minutes, so pipe a web, press one candy eyeball near the center, and tuck a gummy worm beside it before moving on. Candy pressed onto set chocolate falls off the moment someone picks the brownie up.

Let the worm curl over an edge or hang off a corner, as if it is crawling out of the web. Every square ends up with a slightly different face.

Chill the tray for 10 minutes. That is enough to set the chocolate and hold the candy in place, even if you pack the squares in a box with parchment between layers.

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More Halloween Brownie Ideas From the Same Pan

The same 9×13 slab takes other spooky toppings just as well. A few that suit this sturdy cocoa base:

• Mummies: white chocolate piped in zig zag bandages with two eyes peeking out. The full method is in my mummy brownies.
• Ghosts: piped marshmallow ghosts with little chocolate faces, like these ghost brownies.
• Vampire bites: a cream cheese swirl and a raspberry “blood” sauce, as in the vampire brownies.
• Graveyard: crushed chocolate cookies scattered over the top as dirt, with gummy worms half buried in it.
• Monsters: a thin layer of brownie frosting and as many candy eyes as each square can hold.

On a dessert table, brownies sit well next to something spoonable like Halloween dirt cups and something crisp like Halloween sugar cookies.

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Keeping the Webs Sharp for Three Days

Store decorated brownies in an airtight container in a single layer, or with parchment between layers. They keep 3 days at room temperature and up to 5 days in the fridge. In a warm kitchen, choose the fridge, since the webs soften as the room heats up. Take chilled squares out about 20 minutes before serving so the brownie softens again.

To freeze, wrap each square in plastic wrap and pack them into a freezer container for up to 2 months. Thaw them at room temperature without unwrapping. Cold brownies that come out of the wrap too soon collect condensation, and the chocolate turns tacky and streaked.

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Spooky Brownie Questions

Can I use a boxed brownie mix?

Yes. A family size mix baked in a 9×13 pan works for every decorating step here. Bake it as the box says, cool it fully, then cut and decorate the same way.

Can I bake these in an 8×8 pan?

Halve the recipe for an 8×8 pan. The batter is about as deep as in the 9×13, so start checking at 25 minutes. Cut 9 squares and use 9 eyeballs and 9 worms.

How far ahead can I make Halloween brownies?

Bake and cut them up to 2 days ahead and keep them covered at room temperature. Pipe the webs the day before or the morning of the party, when the chocolate looks its glossiest.

Why did my chocolate web crack?

Plain melted chips set hard and brittle. The teaspoon of oil keeps them a little flexible, so the lines bend instead of snapping when a square is picked up.

If you bake these with kids this year, tell me in the comments how the webs turned out. The wonky ones count too.