Rich, fudgy sourdough discard brownies topped with silky chocolate ganache. This easy one-bowl recipe is the perfect way to use up sourdough starter while making bakery-worthy brownies at home.

Hello, dear friends!

I know it feels like I’ve been missing in action, and I promise I haven’t disappeared. I’ve just been over here in my little corner of the world working on something really exciting behind the scenes. I can’t wait to share it with you. But it’s also summer, and if we’re being honest, summer has a funny way of making time disappear.

One minute you’re making ambitious lists of all the things you’re going to do. Farmers markets. Day trips. Backyard dinners. Organizing that closet you’ve been pretending not to see since Christmas.

The next minute it’s 100 degrees outside, you’re hiding in the air conditioning with a giant glass of lemonade, and accomplishing absolutely nothing suddenly feels like a perfectly reasonable life choice.

I’m pretty sure that’s just summer doing what summer does.

Around here, turning on the oven has felt a little like volunteering for a sauna. Every recipe has been followed by me dramatically announcing, “Well…I guess I live here now,” while standing in front of the open freezer.

But then Zander wandered into the kitchen the other day and casually said,

“Hey Mom…you haven’t made brownies in forever.”

You guys.

The gasp I gasped.

Forever? FOREVER?

Clearly my brownie-making reputation was on the line.

Challenge accepted, buddy.

Now, if you’ve been around here very long, you know two things about me. First, I refuse to waste perfectly good sourdough discard. That starter has been with our family for years. At this point it’s basically another member of the household. It deserves better than the trash can.

Second, my kids have taught me that food doesn’t have to look the same for every person to be exactly what they need.

Zander absolutely demolishes Cosmic Brownies. Loves them.

Except…

Because he’s Ivy’s brother, and apparently my children made a pact to keep life interesting, he carefully picks off every single rainbow candy piece before he eats one.

Who does that?

Isn’t the whole point of Cosmic Brownies the colorful little candies?

Apparently not.

So instead of rainbow candies, I gave these brownies something even better—a silky, glossy chocolate ganache that sets into the most beautiful fudgy layer you’ve ever seen. It’s rich without being over-the-top, perfectly chocolatey, and somehow makes these brownies feel like they came from a little neighborhood bakery.

And underneath that gorgeous ganache?

A deeply chocolate brownie that’s chewy around the edges, gloriously fudgy in the middle, and secretly putting that cup of sourdough discard to very good use.

No waste? Check.

Happy sourdough starter? Check.

Happy teenager? Also check.

Now…I’m not going to admit whether Zander ate more brownies than I did because some things are better left between me and the pan. Let’s just say they disappeared suspiciously fast.

For a family that has navigated ARFID for years, moments like this always make my heart smile a little. There is something so wonderful about finding a recipe that everyone happily reaches for without a second thought. Food has always been one of my favorite ways to say, “I love you,” and seeing an empty brownie pan feels like a pretty good conversation.

So yes, I know it’s hot outside.

Yes, your air conditioner may sigh dramatically when you turn on the oven.

And yes, these brownies are absolutely worth it.

Because do you know what goes with warm, fudgy brownies?

Ice cream, my friends.

Ice cream.

If summer insists on being this hot, we might as well lean into it.

Grab a scoop of vanilla, pour yourself a cold glass of milk, and make these for the people you love. I have a feeling you’ll be scraping the last little bits of ganache out of the pan before you know it.

One Bowl Sourdough Discard Brownies with Chocolate Ganache

Why You’ll Love These Brownies – One bowl means less cleanup. – A perfect way to use up sourdough discard. – Thick, fudgy centers with chewy edges. – Glossy chocolate ganache that looks bakery-worthy. – No mixer required. – Absolutely magical with a scoop of vanilla ice cream.

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Ingredients Method Notes

Ingredients

Brownies
– ¾ cup butter
– 1½ cups granulated sugar
– ¾ cup cocoa powder Dutch process or regular…because sometimes the cocoa you already have is good enough.
– 1 large egg room temperature
– 2 large egg yolks room temperature
– 1 teaspoon vanilla bean paste because I’m feeling fancy
– ¼ teaspoon salt
– 100 g sourdough discard
– ½ cup all-purpose flour
– ½ teaspoon espresso powder
– 1 cup semi-sweet chocolate chips
Chocolate Ganache
– 8 ounces dark or semi-sweet chocolate chopped
– 1 cup heavy whipping cream

Method

Preheat your oven to 350°F and line a 9×9-inch baking pan with parchment paper. Leave a little parchment hanging over two sides to make yourself a sling later. Future You will be very thankful.
Grab a large microwave-safe bowl and add the butter and sugar. Yep. Together.
Melt the butter right with the sugar because this little trick is how we're going to get that gorgeous shiny, crinkly brownie top. Now grab your whisk and mix those two together for about 2 minutes. I call this my workout.
Shake out your arms and once everything looks creamy and glossy, whisk in the egg followed by the two egg yolks until completely combined.
Add the vanilla bean paste and whisk again. Now it's time for our secret weapon. Stir in the sourdough discard until it's fully incorporated. Don't worry—you won't taste sourdough. It simply adds moisture and richness while helping you use up something you'd otherwise toss.
Now, people who love every kitchen gadget might sift together the cocoa powder, flour, and espresso powder. Me? I'm adding them right on top. Grab your favorite wooden spoon and gently fold everything together until only a few streaks of flour remain.
Add the chocolate chips and continue folding just until they're mixed in. Please don't overmix. Seriously. Those fudgy brownies you're dreaming about are counting on you.
Spread the batter into your prepared pan, smoothing the top with an offset spatula.
Bake for 32–35 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs. Not wet batter. Not completely clean. Moist crumbs are the sweet spot.
Let the brownies cool completely. And by completely, I mean completely. At least two hours completely. Don't be mad at me, it really is the hardest part of this whole recipe!
Make the Ganache
When your brownies have finally cooled—and your patience has officially run out—it’s time for the ganache.
Place the chopped chocolate into a heatproof bowl.
Heat the heavy cream until it’s steaming and just beginning to simmer around the edges. You want it hot, but not boiling.
Pour the cream over the chocolate.
Now comes another hard part. Walk away. Just walk away and let it sit for 5 minutes because magic takes time.
Then whisk until the chocolate melts into the smoothest, glossiest ganache you’ve ever seen.
Pour it over the brownies and gently spread it to the edges. If you're feeling artistic, give it a few pretty swirls with an offset spatula. Now let the ganache set before slicing. Yes…More waiting. I know, but beautiful, clean brownie slices are worth it!
If your ARFID kiddo isn’t claiming the whole pan, these are absolutely gorgeous topped with rainbow candy-coated chips for that Cosmic Brownie nostalgia—or a sprinkle of flaky sea salt if you’re feeling a little extra.

Notes

High Altitude Tips

Since we’re baking here in Colorado, this recipe has already been tested at high altitude. If you’re baking closer to sea level, keep an eye on the brownies toward the end of the baking time, as ovens can vary.

Christine’s Kitchen Notes

– Dutch-process cocoa gives these brownies a deeper chocolate flavor, but regular cocoa works beautifully too.
– Don’t skip the espresso powder. It doesn’t make the brownies taste like coffee—it simply makes the chocolate taste even more chocolatey.
– Vanilla bean paste is one of my favorite little splurges, but regular vanilla extract works perfectly if that’s what you have.
– Brownies slice beautifully after they’ve chilled for about 30 minutes in the refrigerator.
– These freeze incredibly well, making them dangerous to keep around…because you always know exactly where they are.