This easy lemon blueberry sheet cake is a fruity delight! Made with fresh blueberries and zesty lemon, it’s light, fluffy, and perfect for any occasion.
Plus, the lemon glaze on top adds an extra zing that makes this cake hard to resist. I love serving it at picnics, though I end up eating more than I share! 
Key Ingredients & Substitutions
All-Purpose Flour: This is essential for the cake’s structure. If you’re gluten-free, you can use a gluten-free flour blend. I find that almond flour adds a nice flavor, too!
Buttermilk: Buttermilk adds moisture and tanginess. If you don’t have any, you can make a quick substitute by mixing 1 cup of milk with 1 tablespoon of vinegar or lemon juice. Let it sit for about 5-10 minutes before using.
Fresh Blueberries: These are the star ingredient! You can use frozen blueberries if fresh ones aren’t available. Just remember to thaw and drain them first to avoid excess moisture in your batter.
Unsalted Butter: Using unsalted butter allows you to control the salt in the recipe better. If you’re in a pinch and only have salted butter, it’s okay, just reduce the added salt by a pinch.
How Do You Ensure Fluffy Cake Texture?
Getting a fluffy cake is all about mixing the ingredients properly. Start by creaming the butter and sugar until it’s light and airy. This step introduces air into the mixture, which helps the cake rise. Here’s a little checklist:
- Beat the butter and sugar for about 3-4 minutes.
- Add eggs one at a time, making sure each is fully incorporated before adding the next.
- Alternate adding dry ingredients and buttermilk. This keeps the batter smooth and prevents overmixing.
- Finally, fold in the blueberries gently to avoid crushing them.
By following these tips, you’ll finish with a beautifully fluffy cake every time!
Easy Lemon Blueberry Sheet Cake
Ingredients You’ll Need:
For the Cake:
- 2 ½ cups all-purpose flour
- 2 ½ tsp baking powder
- ½ tsp salt
- ½ cup unsalted butter, softened
- 1 cup granulated sugar
- 3 large eggs
- 1 cup buttermilk
- 1 tbsp lemon zest (about 1 large lemon)
- 2 tbsp fresh lemon juice
- 1 tsp vanilla extract
- 1 ½ cups fresh blueberries (can use frozen, thawed and drained)
For the Frosting:
- 1 cup unsalted butter, softened
- 4 cups powdered sugar, sifted
- 2 tbsp fresh lemon juice
- 1 tsp lemon zest
- 2-3 tbsp fresh blueberry puree (or blueberry jam)
- Optional: lemon slices for garnish
How Much Time Will You Need?
This delicious lemon blueberry sheet cake requires about 15 minutes of prep time and 35-40 minutes of baking. After baking, let it cool completely, which will take about an hour. So in total, you’re looking at around 2 hours for the entire process, including cooling and frosting. Worth the wait, trust me!
Step-by-Step Instructions:
1. Prepare the Oven and Pan:
Start by preheating your oven to 350°F (175°C). Grease and flour a 9×13-inch sheet pan to ensure the cake doesn’t stick after baking.
2. Mix Dry Ingredients:
In a medium bowl, whisk together the flour, baking powder, and salt. This mixture will help your cake rise nicely, so set it aside for now.
3. Cream Butter and Sugar:
In a large mixing bowl, use an electric mixer to cream the softened butter and granulated sugar together until it’s light and fluffy—about 3-4 minutes. This step is key for a fluffy cake!
4. Add Eggs:
Add the eggs one at a time, making sure to beat well after each one. This helps to incorporate air into the batter, ensuring a nice rise.
5. Add Flavors:
Next, mix in the lemon zest, lemon juice, and vanilla extract. Your kitchen should smell amazing right about now!
6. Combine Wet and Dry Ingredients:
Now, it’s time to mix! Alternately add the reserved dry ingredients and the buttermilk to the wet mixture. Start and finish with the dry ingredients, mixing just until combined. Be careful not to overmix!
7. Fold in the Blueberries:
Gently fold in the blueberries using a spatula or wooden spoon, being careful not to crush them. We want lovely whole blueberries in the cake!
8. Pour and Bake:
Pour the batter into the prepared sheet pan, spreading it out evenly. Bake in the oven for 35-40 minutes or until a toothpick inserted into the center comes out clean. Yum!
9. Cool the Cake:
Once baked, remove the cake from the oven, and let it cool completely in the pan on a wire rack. This could take about an hour.
10. Make the Frosting:
While the cake is cooling, prepare the frosting. Start by beating the softened butter until creamy. Gradually add the sifted powdered sugar, about 1 cup at a time, alternating with lemon juice until it’s fluffy and well combined.
11. Add Flavor to the Frosting:
Add in the lemon zest and blend in the blueberry puree or jam. This will give your frosting a lovely color and delicious flavor!
12. Frost the Cake:
Once the cake is entirely cool, generously spread the blueberry lemon frosting over the top of the cake. It should look fabulous!
13. Garnish and Serve:
If you’d like, top each piece with a fresh lemon slice for an extra touch. Then cut into squares and serve. Enjoy every bite of this light, fruity, and refreshing lemon blueberry treat!
Frequently Asked Questions (FAQ)
Can I Use Frozen Blueberries Instead of Fresh?
Yes, you can use frozen blueberries! Just make sure to thaw and drain them first to avoid excess moisture in your batter. Gently fold them in to avoid breaking the berries.
How Should I Store Leftover Cake?
Store any leftover cake in an airtight container at room temperature for up to 3 days. If you want to keep it longer, you can refrigerate it for up to a week or freeze individual pieces wrapped tightly in plastic wrap for up to 3 months.
Can I Make This Cake Ahead of Time?
Absolutely! You can bake and frost the cake a day in advance. Just store it covered in the fridge. Let it sit at room temperature for a bit before serving for the best flavor and texture.
Can I Substitute the Buttermilk?
Yes! If you don’t have buttermilk on hand, you can create a substitute by mixing 1 cup of milk with 1 tablespoon of vinegar or lemon juice. Let it sit for about 10 minutes until it thickens slightly before using.
