Instructions

Step 1: Preheat the oven to 350°F (175°C). Prepare an ungreased 10-inch tube pan; do not grease the pan as the batter needs to cling to the sides.

Step 2: In a medium bowl, sift together the cake flour, ½ cup of granulated sugar, and salt at least 3-4 times. Set aside.

Step 3: In a large, clean bowl, beat the room temperature egg whites on medium speed until foamy. Add cream of tartar and increase the speed to medium-high.

Step 4: Gradually add the remaining 1 cup of sugar, 1-2 tablespoons at a time, letting each addition dissolve before adding more. Beat until firm, glossy peaks form.

Step 5: Fold in the lemon zest and vanilla or lemon extract gently into the egg white mixture.

Step 6: Sprinkle one-third of the sifted flour mixture over the egg whites. Gently fold in with an upward motion. Repeat with the remaining flour mixture in two additions, being careful not to deflate the batter.

Step 7: Toss the blueberries lightly with the all-purpose flour to prevent sinking. Gently fold the blueberries into the batter.

Step 8: Spoon the batter evenly into the ungreased tube pan. Run a knife through the batter to remove large air pockets.

Step 9: Bake for 35-45 minutes until the cake is golden, springs back when touched, and a toothpick inserted near the center comes out clean.

Step 10: Immediately invert the pan onto cooling feet or over a bottle neck to cool completely upside down for 1½ to 2 hours to prevent collapse.

Step 11: Once cooled, run a thin knife around the edges, invert onto a serving plate, slice carefully with a serrated knife, and enjoy!

Tips & Variations

Use room temperature egg whites for maximum volume; if needed, warm them gently in a bowl of warm water before beating.

Make sure all bowls and utensils are grease-free to ensure egg whites whip properly.

Coat blueberries with flour to keep them suspended in the batter and prevent sinking.

Experiment with lime or orange zest for a different citrus twist.

Substitute raspberries or chopped strawberries for blueberries, but toss them in flour first and be aware they may release more moisture.

If you don’t have cake flour, make a substitute by mixing 1 cup all-purpose flour minus 2 tablespoons, plus 2 tablespoons cornstarch, sifted together.

Storage

Store the cake in an airtight container at room temperature for 2-3 days to keep it moist and fresh. Refrigerate if your kitchen is warm or if the cake has fresh fruit toppings, covering tightly to prevent drying, for up to 5 days. To freeze, wrap tightly in plastic and foil and store for 2-3 months; thaw at room temperature before serving. Avoid microwaving to keep the delicate texture intact.

FAQs

Can I use frozen blueberries instead of fresh?

Fresh blueberries are best because frozen tend to release too much moisture, which can weigh down the delicate batter. If using frozen, toss them in flour and drain excess liquid before folding in, but results may vary.

Why do I need to cool the cake upside down?

Cooling upside down prevents the angel food cake from collapsing while it sets. This helps maintain its height and airy texture by allowing the structure to stabilize as it cools.