This sourdough sugar cookie cake is a cozy, festive twist on my viral sugar cookie bars, and it might just be my new favorite way to serve them. I’ve adapted the original recipe into a soft, thick cookie-cake hybrid that bakes up beautifully in a sheet pan with tender edges and a melt-in-your-mouth center.
It’s the kind of dessert that feels both nostalgic and celebratory, whether you decorate it with a flag design for the 4th of July or keep it simple for any occasion. Topped with a light whipped frosting and fresh fruit, it’s the perfect mix of comfort and fun.
Why I love this recipe
- The texture is unbeatable—soft and thick with a unique cookie-meets-cake feel that’s both cozy and satisfying.
- Perfect for decorating—whether it’s a flag for the 4th of July or a fun design for birthdays or celebrations.
- A great way to use up sourdough discard in a dessert that feels special but is easy to make.
- Convenience: Stays moist and tender for days, making it ideal for make-ahead treat.
Tips for success
- Cool Completely: Allow the cookie cake to cool completely in the pan before cutting to prevent them from falling apart.
- Room Temperature Ingredients: Use room temperature ingredients to ensure even mixing and a smooth batter.
- Measure Accurately: Weigh your ingredients for precise measurements, especially the flour and sugar, to achieve the desired consistency.
- Sourdough discard: I recommend using discard no more than a week old as this may result in a sour result.
- Do Not Overmix: Mix the batter just until combined to avoid developing too much gluten, which can result in tough cookie bars.
How to make sourdough sugar cookie cake: step-by-step
- 226 grams unsalted butter, softened
- 275 grams sugar
- 2 large eggs, room temperature
- 200 grams sourdough discard (no more than a week old & brought to room temp)
- 14 grams (1 tablespoon) vanilla extract
- 280 grams all-purpose flour
- 6 grams baking powder
- 4 grams salt
- 6 grams cornstarch
- 80 grams of festive sprinkles (optional)
For the whipped cream frosting
- 4 tablespoons (¼ cup) unsalted butter, softened
- 3 cups (360 grams) powdered sugar
- 4–6 tablespoons heavy cream (start with 4 and adjust for consistency)
- 2 teaspoons vanilla extract
- a pinch or 2 of salt to cut the sweetness
- fruit for decorating (blueberries, strawberries, raspberries, etc.)
Equipment
- 1 9×13 in cake pan
- parchment paper
- food scale
- mixing bowl
- hand mixer or stand mixer
Instructions
- Preheat the oven to 350°F (175°C) and line a 9×13 inch baking pan with parchment paper.
- Cream the butter and sugar together in a large bowl until light and fluffy (about 2–3 minutes). You can use a hand mixer or stand mixer for this step.
- Add the eggs, sourdough starter, and vanilla extract to the bowl. Mix until well combined and smooth.
- In a separate bowl, whisk together the flour, baking powder, salt, and cornstarch. If using sprinkles, coat them in the dry mixture to prevent sinking.
- Gradually mix the dry ingredients into the wet mixture, stirring just until combined. Be careful not to overmix. The mixture should be thicker than cake batter but softer than traditional sugar cookie dough.
- Spread the dough evenly into the prepared baking pan. Use a spatula or floured hands to press it into the corners and smooth the top. Note: this is a wetter sugar cookie cake dough, this is normal. It helps achieve optimal texture. It requires a little elbow grease to spread it, but I promise it is worth it!
- Bake for 28-32 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out clean.
- Let the cookie cake cool in the pan for 20-30 minutes before transferring to a wire rack to cool completely.
How to make the frosting
- In a medium bowl, beat the softened butter until smooth.
- Add the powdered sugar, 3 tablespoons of heavy cream, vanilla extract, & pinches of salt. Beat until smooth and fluffy. Add the remaining tablespoons of cream to reach your desired consistency. I like using the full 6 tablespoons for a whipped cream texture.
- Spread the frosting over the cooled sugar cookie cake and decorate with festive fruit or sprinkles if desired.
- Cut into squares to serve and enjoy!
- Storage: Store any leftover sugar cookie cake in an airtight container at room temperature for up to 2 days, or refrigerate for up to 5 days to keep it fresher longer. If frosted, it’s best to keep it chilled, especially in warmer weather. Let it come to room temp before serving for the best texture.
More sourdough dessert recipes
Sourdough Sugar Cookie Cake (soft & chewy)
This sourdough sugar cookie cake is soft, thick, and perfectly sweet, a cookie-meets-cake treat topped with whipped frosting and fresh fruit, perfect for any celebration.
Servings: 1 9×13 inch cake
Equipment
- 1 9×13 inch cake pan
- Parchment paper
- Food scale
- Mixing bowls
- Hand mixer or stand mixer
Ingredients
- 226 grams unsalted butter softened
- 275 grams sugar
- 2 large eggs room temperature
- 200 grams sourdough discard no more than a week old, room temperature
- 14 grams (1 tablespoon) vanilla extract
- 280 grams all-purpose flour
- 6 grams baking powder
- 4 grams salt
- 6 grams cornstarch
- 80 grams festive sprinkles optional
For the whipped cream frosting
- 4 tablespoons (1/4 cup) unsalted butter softened
- 2 & 2/3rd cup (320 grams) powdered sugar
- 4-6 tablespoons heavy cream start with 4 and adjust as needed
- 2 teaspoons vanilla extract
- a pinch or 2 of salt to cut the sweetness
- fruit for decorating blueberries, strawberries, raspberries, etc.
Instructions
- Preheat the oven to 350°F (175°C) and line a 9×13 inch baking pan with parchment paper.
- Cream the butter and sugar together in a large bowl until light and fluffy (about 2–3 minutes). You can use a hand mixer or stand mixer for this step.
- Add the eggs, sourdough starter, and vanilla extract to the bowl. Mix until well combined and smooth.
- In a separate bowl, whisk together the flour, baking powder, salt, and cornstarch. If using sprinkles, coat them in the dry mixture to prevent sinking.
- Gradually mix the dry ingredients into the wet mixture, stirring just until combined. Be careful not to overmix. The mixture should be thicker than cake batter but softer than traditional sugar cookie dough.
- Spread the dough evenly into the prepared baking pan. Use a spatula or floured hands to press it into the corners and smooth the top. Note: this is a wetter sugar cookie cake dough, this is normal. It helps achieve optimal texture. It requires a little elbow grease to spread it, but I promise it is worth it!
- Bake for 28-32 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out clean.
- Let the cookie cake cool in the pan for 20-30 minutes before transferring to a wire rack to cool completely.
How to make the frosting
- In a medium bowl, beat the softened butter until smooth.
- Add the powdered sugar, 3 tablespoons of heavy cream, vanilla extract, & pinches of salt. Beat until smooth and fluffy. Add the remaining tablespoons of cream to reach your desired consistency. I like using the full 6 tablespoons for a whipped cream texture.
- Spread the frosting over the cooled sugar cookie cake and decorate with festive fruit or sprinkles if desired.
- Cut into squares to serve and enjoy!
- Storage: Store any leftover sugar cookie cake in an airtight container at room temperature for up to 2 days, or refrigerate for up to 5 days to keep it fresher longer. If frosted, it's best to keep it chilled, especially in warmer weather. Let it come to room temp before serving for the best texture.
Notes
Sourdough discard: Ensure your sourdough discard is no more than week old to avoid a sour taste in the sugar cookie bars. Active starter can be used.
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