Measure the Flour ProperlyStart by stirring the all-purpose flour to loosen it. Then, use the spoon and sweep method: Spoon the flour into a 1-cup dry measuring cup until it overflows. Use the back of a butter knife or the straight edge of a wooden spoon to level off the excess without packing it down.

Replace Some Flour with CornstarchFrom the measured flour, remove two tablespoons and set it aside. Replace the removed flour with two tablespoons of cornstarch.

Combine and SiftWhisk or sift the flour and cornstarch together at least once to ensure they are evenly distributed. Sifting helps create a finer texture, more closely resembling cake flour.

Now, your homemade cake flour substitute is ready to use! Simply measure it as you would store-bought cake flour in your recipe.