Line the bottom of your 9-inch cake pan with parchment and lightly grease the sides. This ensures easy release and perfect shape.
Place the egg whites in a medium bowl and the yolks in a larger bowl. Beat the whites until soft peaks form and set aside. This gives the cake its fluffy texture.
In the large bowl with yolks, whisk in the honey, Greek yogurt, oil, vanilla extract, and lemon zest. Stir until smooth and creamy.
In a separate bowl, mix flour, baking powder, baking soda, and salt. Slowly add this to the wet mixture, stirring until just combined. Don’t overmix — it keeps the cake tender.
Gently fold in one-third of the egg whites to lighten the batter, then fold in the rest. Be careful not to deflate the mixture.
Toss the blueberries in 1 tablespoon of flour to prevent them from sinking to the bottom. Then fold them into the batter gently.
Pour the batter into the prepared pan, spreading it evenly. Bake for 35–40 minutes or until a toothpick inserted in the center comes out clean.
Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack. Slice and enjoy warm or chilled.