You don't preheat your oven
THE RESULT: Uneven outcomes .
THE FIX: An oven that hasn’t been preheated may not drastically affect casseroles, but it will have a noticeable effect on baked goods. Placing baked goods in ovens that haven’t reached the specified temperature can cause problems with texture, color, and rise. Baked goods can also end up “done” long before the rise is complete or before they’ve sufficiently browned. The best advice: Always preheat to avoid having any surprises emerge from your oven.