Name: Lemon Blueberry Sheet Cake
Prep time: 20 min
Cook time: 45 min
Total time: 65 min
Ingredients: 3 cups all-purpose flour; 2 teaspoons baking powder; 1/2 teaspoon baking soda; 1 1/4 teaspoons salt; 1 cup butter (softened); 1 1/2 cups granulated sugar (creamed with butter until light and fluffy); 4 large eggs (room temperature); 1 cup buttermilk (room temperature); 2 teaspoons vanilla extract; 1/4 cup lemon juice; 2 lemons zest (about 2 teaspoons zest); 1 1/2 cups fresh blueberries (tossed with 1 tablespoon flour); 2 1/2 cups powdered sugar; 1/3 cup lemon juice (for glazing)

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A Slice of Summer in My Kitchen

If you close your eyes and imagine warm lemon scent drifting through the house while blueberries pop like little jewels in a golden crumb, you’ll know why I make this Lemon Blueberry Sheet Cake whenever the season tips toward sunny. I first baked it on a rainy Saturday to cheer up a friend, and the whole block seemed to catch a whiff and wander over. If you like the idea of lemon and blueberry in other forms, I sometimes send folks to a recipe for lemon and blueberry cheesecake tarts when they want a fancier bite-sized version, but there’s something so honest and immediate about a sheet cake that it’s my go-to.

The Ingredients You’ll Need (and how they behave)

I never hand someone a list without a little story, so here it is woven into what I notice as I measure: the dry backbone is 3 cups all-purpose flour, 2 teaspoons baking powder, 1/2 teaspoon baking soda, and 1 1/4 teaspoon salt. For richness you’ll want 1 cup butter (2 sticks), softened, creamed with 1 1/2 cups granulated sugar until light and fluffy. Brightness comes from the juice and zest of 2 lemons (about 1/4 cup lemon juice), and for lift and structure I use 4 large eggs and 1 cup buttermilk, with 2 teaspoons vanilla extract to soften the flavors. The star bursts of fruit are 1 1/2 cups fresh blueberries, tossed with 1 Tbs flour so they don’t all sink. For the glossy finish I whisk together 2 1/2 cups powdered sugar with 1/3 cup lemon juice for a glaze that sings.

Mentioning quantities like this makes it feel more like I’m standing at the counter with you, spoon in hand. The buttermilk keeps the crumb tender and gives the lemon something to sit on rather than cutting through harshly.

Baking It Up and the Important Steps

There are a few points where I pay extra attention, and the routine is simple. Preheat the oven to 350 degrees F. Grease a 9×13 baking dish, and line with parchment paper so there’s an overhang over the two long sides of the pan. This will make removing the cake much easier! In a medium mixing bowl, whisk together the dry ingredients, flour through salt. Set aside. In a stand mixer fitted with the paddle attachment (or hand mixer), cream together the sugar and butter until light and fluffy. Add the eggs and vanilla, and buttermilk, and mix on low until incorporated. Add the dry ingredients, and mix until no streaks of flour remain. Mix in the lemon juice and zest. Gently stir in the blueberries with a spatula. Pour the cake batter into the prepared 9×13 baking dish, and bake for about 40-45 minutes, or until a toothpick comes out with moist crumbs. Allow to cool completely. You can lift the cake out of the pan before drizzling, or leave it in the dish to serve. Either way works! For the glaze: combine the powdered sugar and lemon juice, and pour over the cooled cake. Let the glaze harden, and then garnish with fresh fruit and serve!

I always pause at the blueberry step and fold gently. Overworking crushes the berries and streaks the batter with purple. Also, tossing the berries with a tablespoon of flour helps them suspend in the batter rather than sinking to the bottom.

Little Tricks I Use

One stubborn piece of advice I repeat to friends is to line the pan with parchment so you get neat slices when you lift the whole cake out. Another is to let it cool fully before glazing; warm cake will make the glaze sink right in and you’ll lose that pretty sheen. If you’re in a hurry, chilling the cake briefly in the refrigerator after it cools speeds up the glazing step without harming texture.

When I test for doneness, I don’t rely on timing alone. The cake should be lightly golden at the edges and spring back when you press gently in the center. The toothpick test is the final word: you want moist crumbs, not raw batter. If the top starts getting too brown before the middle is done, I tent the pan with foil for the last 10 minutes.

A couple of small personal tips: always bring the butter and eggs to room temperature for even mixing; use fresh lemons for zest and juice because bottled lemon tastes flat; and if blueberries aren’t super sweet, add an extra tablespoon of sugar to the batter so the lemon doesn’t dominate.

When I Tweak It or Make It Different

I love how forgiving this cake is. For a sturdier, snackable version that’s more candy-like, I once riffed on the flavors and made a riff that reminded guests of a playful mix—if you’re curious about creative blueberry-lemon treats, take a peek at this unique blueberry lemon cheesecake puppy chow treat for inspiration. For a breakfast or brunch vibe, swap some of the sugar for maple syrup and serve with coffee; I sometimes pair it with a flurry of mini pancakes and fruit and it becomes a brunch centerpiece. If you want a true brunch spin, look at ideas for sheet-pan breakfasts that could sit beside this cake, like the flavors in a 4-way sheet-pan pancake I tried once when feeding a crowd.

Other variations I play with are adding a sprinkle of lemon poppy seeds for texture, folding in a handful of chopped toasted almonds for nuttiness, or using frozen blueberries right from the bag if fresh ones aren’t available—just toss them in flour first and expect slightly more moisture in the crumb.

The Best Part About Serving This

I always serve this cake slightly chilled or at room temperature. The glaze should be set so each slice keeps its signature look: pale, glossy, and flecked with zest. It isn’t shy — the lemon is bright but rounded by butter and buttermilk, and the blueberries give little pockets of sweet-tart surprise. It pairs beautifully with simple whipped cream, vanilla ice cream, or a pot of strong tea. For casual company I’ll leave it in the dish and let people help themselves; for a special day I lift it out with the parchment overhang and slice it into neat squares that look like they were made in a bakery.

If you have leftovers, wrap them tightly and refrigerate; the glaze helps seal in moisture so the cake stays good for about 3 to 4 days. You can freeze individual slices wrapped well for up to a month—thaw in the fridge overnight and bring to room temperature before serving.

Conclusion

If you want to see another take on this exact combination of flavors, there’s a lovely version online that inspired my first try — take a look at Lemon Blueberry Sheet Cake – This Celebrated Life for more baking inspiration.