A cloud-like Swedish Coffee Cake with a subtle whisper of lemon and a sweet, spiced crackly crumb topping. The secret to its lightness is folding in stiffly beaten egg whites.
Preheat oven to 350°F. Lightly grease a 13x9 inch baking pan.
Cream the softened butter and sugar in a large bowl for 3-4 minutes until pale and fluffy.
Add egg yolks one at a time, beating well after each addition until smooth.
Sift the flour, baking powder, and salt into the butter mixture. Stir gently.
Add milk, vanilla, lemon juice, and lemon zest. Stir until just combined.
In a clean bowl, beat egg whites until stiff peaks form. Gently fold them into the batter using a rubber spatula.
Pour batter into the prepared pan and spread evenly.
Mix crumb topping ingredients in a small bowl and scatter evenly over the raw batter.
Bake for 40 minutes or until a toothpick inserted in the center comes out clean.
Notes
Ensure your egg white bowl is completely grease-free for proper volume. For measuring flour, fluff it first then spoon into the cup to avoid a dense cake.