Select the substitute that is safe for you (Substitutes that do not match free or diet icons may appear.)
ALWAYS check labels before buying or consuming!
Preheat oven to 350°F (180°C). Grease and line pan.
Mix butter, sugar, zest, and vanilla until creamy, then beat in remaining ingredients until batter is nice and smooth.
Bake 30 min.
If top browns too much, cover with tin foil.