Long-Fermented Sourdough Brown Butter Carrot Cake

Celebrate the arrival of spring with this Long-Fermented Sourdough Brown Butter Carrot Cake—a fresh, festive twist on a classic favorite. With tender layers infused with warm spices, nutty brown butter, and the subtle tang of sourdough, this cake is everything you want for your Easter table or a sunny weekend gathering. Finely grated carrots and citrus zest bring brightness, while the crunchy pecan brown sugar streusel adds a delicious contrast. Topped with a luscious cream cheese frosting, it’s the perfect bake to welcome longer days, blooming flowers, and joyful moments with loved ones.

Whether you’re hosting Easter brunch, a spring picnic, or just indulging in a little seasonal baking, this cake rises to the occasion—literally and flavorfully.

As an amazon affiliate, this post may contain affiliate links. Which means I may receive a commission for qualifying purchases. I will only recommend products that I personally love and use.

Why You’ll Love This Recipe

This cake boasts an overnight fermentation with the addition of sourdough discard, which aids in breaking down the gluten making this cake easily digestible. But if you choose- you can skip this step and just use up extra discard if you want to make this cake quickly in a pinch! This cake is perfectly moist, and very easy for a beginner to make.

Brown butter adds depth of flavor, while the addition of orange zest and maple flavor contrast perfectly with the earthy carrot. Add lush cream cheese frosting, and top with spiced brown sugar pecan streusel for the perfect crunch.

Tools You’ll Need

For the Cake:

• Mixing bowls- (large and medium)- for mixing batters

• Whisk, hand beaters, and rubber spatula- for combining ingredients

• Microplane or zester- (for orange zest)

• Box grater or food processor- (for finely grating carrots)

• Saucepan or small pot- (for browning butter)

• Kitchen scale (optional)- for accurate measuring—especially helpful with sourdough baking

• Measuring cups and spoons- if not using a scale

• Cake pans- two 8-inch round pans or one 9x13-inch pan (I love these 9 inch cake pans linked here for even baking https://amzn.to/4iwpJMH or this 9x13 USA pan for sheet cakes https://amzn.to/4iPzJQO)

• Parchment paper- (optional) for lining pans

• Cooling rack- for cooling cakes

• Toothpick or cake tester- to test when cake is done

For the Streusel:

• Small mixing bowl- for mixing nuts

• Baking sheet- to toast pecans

• Spatula- for tossing and breaking up streusel while baking

Optional but Helpful:

• Offset spatula- for spreading frosting

• Cake stand or platter- for serving

• Bench scraper or frosting spatula- for clean cake sides if frosting

Gather your supplies- now bakers- let's bake a cake!

Ingredients for Cake:

Overnight Fermented Base:

• 320g (2½ cups) all-purpose flour

• 138g (10 tbsp) avocado oil

• 120g (½ cup) sourdough starter (100% hydration, unfed)

• 2 tsp vanilla extract

• 1 tsp maple flavoring (optional, I use Frontier Co-op Maple flavoring linked here https://amzn.to/41O9qUl)

• 100g (½ cup) granulated sugar

• 200g (1 cup, packed) brown sugar

• 120g (⅓ cup) honey

• 150g (⅔ cup) whole milk

• 120g (½ cup) sour cream

Add the Next Morning:

• 113g (½ cup) butter, browned

• 2 large eggs + 2 egg yolks (134g total)

• 240g (2 cups) finely grated carrots

• 1 tbsp (8g) orange zest

• 2 tsp baking powder

• 1½ tsp baking soda

• ½ tsp salt

• 2 tsp ground cinnamon

• 1 tsp ground ginger

• ½ tsp ground nutmeg

• ¼ tsp ground cardamom

Cake Instructions

Baker's Schedule: 8:00 PM- Day 1

Step 1: Overnight Fermentation

1. In a large mixing bowl, whisk together the oil, sourdough starter, vanilla, maple flavoring (if using), sugars, honey, milk, and sour cream.

2. Cover and refrigerate overnight (8–12 hours).

Note: if making the pecan streusel and fermenting, you will be preparing this as well night before. Please refer to instructions listed below to see steps needed to start fermentation.

Baker's Schedule: 8:00 AM- Day 2

Step 2: Mix Remaining Ingredients into Batter

1. Brown the butter in a saucepan over medium heat until golden and fragrant. Let it cool slightly.

2. Grate carrots finely and prepare the dry ingredients.

3. To the fermented base, add browned butter, eggs and yolks, and all remaining dry ingredients. Beat with hand beaters until batter is smooth- about 1 minute.

4. Fold in grated carrot and orange zest. Don't overbeat your batter.

If you choose to skip overnight fermentation, follow the steps below to combine cake batter.

Combine wet ingredients in a large bowl with hand beaters:

• 138g (10 tbsp) avocado oil

• 120g (½ cup) sourdough starter (100% hydration, unfed)

• 2 tsp vanilla extract

• 1 tsp maple flavoring (optional, I use Frontier Co-op Maple flavoring linked here https://amzn.to/41O9qUl)

• 100g (½ cup) granulated sugar

• 200g (1 cup, packed) brown sugar

• 120g (⅓ cup) honey

• 150g (⅔ cup) whole milk

• 120g (½ cup) sour cream

• 113g (½ cup) butter, browned

• 2 large eggs + 2 egg yolks (134g total)

Whisk dry ingredients in a separate bowl:

• 320g (2½ cups) all-purpose flour

• 2 tsp baking powder

• 1½ tsp baking soda

• ½ tsp salt

• 2 tsp ground cinnamon

• 1 tsp ground ginger

• ½ tsp ground nutmeg

• ¼ tsp ground cardamom

Add dry ingredients to wet, and mix with hand beaters until batter is just smooth. Be careful not to overmix your batter.

Fold into your batter:

• 240g (2 cups) finely grated carrots

• 1 tbsp (8g) orange zest

Step 3: Bake

1. Preheat oven to 350°F (175°C).

2. Grease and flour two 8-inch cake pans or one 9x13-inch pan. Tap excess flour out of pans. Optionally, line bottoms of cake pans with parchment to make cakes release faster.

3. Pour the batter evenly into the prepared pan(s).

4. Bake for 40–45 minutes (round pans) or 45–50 minutes (9x13-inch).

5. A toothpick inserted in the center should come out clean.

6. Cool in pans for 10 minutes, then transfer to a wire rack to cool completely. To make cakes easier to frost, wrap with plastic and place on a cookie sheet to refrigerate cakes. You can also freeze them after wrapping if you choose to frost cakes at a later time.

Fermented Pecan Brown Sugar Streusel

This sweet, spiced streusel adds crunch and flavor to the top of the cake. Note: For a nut-free version, simply omit the pecans.

Ingredients:

• 75g (⅓ cup) brown sugar

• 75g (½ cup) all-purpose flour

• ½ tsp ground cinnamon

• ⅛ tsp ground cardamom

• ⅛ tsp ground nutmeg

• 57g (¼ cup) salted butter, softened (add ¼ tsp sea salt if using unsalted butter)

• 120g (1 cup) pecans, whole or chopped

• 30g (2 tbsp) sourdough discard

Instructions

1. In a small bowl, toss pecans (if using) with sourdough discard until coated. If you choose to not use pecans, skip this step and add discard to dry ingredients with softened butter.

2. Add softened butter, brown sugar, flour, and spices.

3. Mix with your hands until crumbly. Spread streusel onto a baking sheet lined with parchment or a silicone mat and cover with plastic or a lint-free cloth. Allow to ferment overnight at room temperature.

4. The next morning, preheat oven to 325 F. Bake at 325°F (160°C) for 10 minutes. Toss pecans, and bake for another 10 minutes until golden and crisp. Cool completely before using as a topping.

Prepare your frosting while your cakes and topping cool.

Cream Cheese Frosting

Ingredients:

• 225g (8 oz) cream cheese, softened

• 112g (½ cup) unsalted butter, softened

• 450g (about 3¾ cups) powdered sugar

• 1 tsp vanilla extract

• Pinch of salt (1/4 tsp)

Note: this makes enough frosting to cover a 9x13 sheet cake. If making a two-tier 9 inch cake, double this recipe.

Instructions:

1. Beat cream cheese and butter together until smooth and fluffy with hand mixers. Scrape sides of bowl down if needed to make sure cream cheese and butter and completely combined and fluffy.

2. Add vanilla and salt, and beat into mixture.

3. Sift powdered sugar if desired (makes less clumps and a smoother consistency). Gradually beat in powdered sugar until light and creamy.

Assembling your Cake:

If making a 9x13 single sheet cake, spread frosting over the top of the cake and sprinkle generously with the pecan streusel. If you choose to make a two-layer cake, place one layer on a serving plate. Spread frosting on top and sides, fully coating first layer of cake. Add the second layer and frost the top and sides. Refrigerate 30 minutes to firm up the icing, and then add pecan streusel to the sides of the cake. Slice and Serve!

How to pipe mini carrots: I decorated my cake with tiny carrots all over randomly by coloring a bit of left over frosting orange and green. Use Wilton tip #5 with the orange frosting to pipe the a thicker line, pulling the end down to create a carrot. Add the carrot tops with green frosting with Wilton tips #2 or #1 making small lines at the top of the carrots.

Storage & Make-Ahead Tips

• Make ahead: Fermented base and streusel can be prepped the day before.

• Storage: Store the frosted cake in the fridge (airtight) for up to 5 days.

• Freezing: Wrap unfrosted cake layers tightly and freeze for up to 2 months. Thaw overnight in the fridge before frosting.

Yields: Two 8-inch layers or one 9x13-inch cake

This Sourdough Brown Butter Carrot Cake is warm, spiced, tangy, and utterly decadent. The fermented base keeps it moist, the streusel adds crunch, and the cream cheese frosting ties it all together. Whether you’re baking for a holiday, brunch, or just for fun—this one’s a keeper.

Click here to view my shop and see what I use to make my recipes!