To make this Lemon–Orange Olive Oil Cake gluten-free, replace the all-purpose flour with a high-quality gluten-free 1:1 baking blend that includes xanthan gum or another binding agent. Because gluten-free flour blends absorb liquid differently, reduce the sherry or other liquid by 2 tablespoons for better structure. Mix the batter gently to maintain airiness, and extend the baking time by 5–8 minutes if needed. The result is a beautifully tender, aromatic cake with the same delicate citrus notes and moist crumb — entirely gluten-free but every bit as elegant.