Bea’s Blueberry Sheet Cake

---

Soft, tender, and loaded with juicy blueberries in every single bite — a beautifully simple, old-fashioned sheet cake with a moist, buttery crumb and a sweet vanilla cream cheese frosting that takes it completely over the top. The kind of humble, beloved cake that gets passed around at church potlucks and family gatherings and always comes home on an empty pan.

INGREDIENTS

• 2.5 cups all-purpose flour
• 1 teaspoon baking powder
• 0.5 teaspoons baking soda
• 0.5 teaspoons salt
• 0.75 cups unsalted butter, softened
• 1.5 cups granulated sugar
• 3 large eggs, room temperature
• 1 teaspoon vanilla extract
• 1 teaspoon lemon zest
• 1 cup sour cream, room temperature
• 0.25 cups whole milk, room temperature
• 2.5 cups fresh or frozen blueberries
• 1 tablespoon all-purpose flour (for tossing blueberries)
• 8 ounces cream cheese, softened (for frosting)
• 0.5 cups unsalted butter, softened (for frosting)
• 3 cups powdered sugar, sifted (for frosting)
• 2 tablespoons whole milk or heavy cream (for frosting)
• 1 teaspoon vanilla extract (for frosting)
• pinch of salt (for frosting)
• fresh blueberries, for garnish (optional)

STEPS

1. Preheat and prep: Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking pan generously with butter and line with parchment paper leaving an overhang on the long sides for easy lifting. Set aside.
2. Mix the dry ingredients: In a bowl, whisk together the flour, baking powder, baking soda, and salt until evenly combined.
3. Toss the blueberries: In a small bowl, toss the blueberries with the tablespoon of flour until lightly coated. This prevents them from sinking to the bottom of the cake during baking and distributes them beautifully throughout every slice.
4. Cream butter and sugar: Beat the softened butter and granulated sugar together on medium-high speed for 4–5 minutes until very pale, light, and fluffy. Scrape down the sides frequently.
5. Add eggs and flavorings: Add the eggs one at a time, beating well after each addition. Add the vanilla extract and lemon zest and mix until combined.
6. Add sour cream and dry ingredients: In a small bowl stir together the sour cream and whole milk. Add the dry ingredients to the butter mixture in three additions alternating with the sour cream mixture, beginning and ending with the dry ingredients. Mix on low after each addition until just combined. Do not overmix.
7. Fold in the blueberries: Gently fold the flour-coated blueberries into the batter with a few wide, sweeping strokes. Keep the batter light and the blueberries as intact as possible.
8. Bake: Spread the batter evenly into the prepared pan. Bake at 350°F for 35–42 minutes until the top is deep golden brown, the edges have pulled away slightly from the sides, and a toothpick inserted into the center comes out clean or with just a few moist crumbs. Let cool completely in the pan before frosting.
9. Make the frosting: Beat the softened cream cheese and butter together on medium-high speed for 3–4 minutes until completely smooth and fluffy. Add the sifted powdered sugar one cup at a time, beating well after each addition. Add the milk or cream, vanilla extract, and pinch of salt and beat on high for 2 minutes until the frosting is light, smooth, and perfectly spreadable.
10. Frost and serve: Spread the cream cheese frosting generously and evenly over the completely cooled cake. Scatter fresh blueberries over the top if desired. Slice into squares and serve.

NOTES Tips: Tossing the blueberries in flour before folding them in is essential — without it they will all sink to the bottom of the pan and pile up on the underside of the cake when inverted. Fresh blueberries give the most vibrant, beautiful result but frozen work perfectly well — do not thaw frozen berries before using or they will bleed into the batter and turn it purple. Sour cream is the key to an extraordinarily moist, tender crumb that stays fresh for days — do not substitute. The lemon zest in the batter brightens and lifts the blueberry flavor dramatically — do not skip it. The cake must be completely cool before frosting — even slightly warm cake will melt the cream cheese frosting and it will slide off. This cake keeps refrigerated covered for up to 4 days — bring to room temperature for 30 minutes before serving for the best flavor and texture.