It’s easy to under-bake zucchini bread, especially with chocolate chips as the chocolate can often make it difficult to perform an accurate toothpick test. If you find that your Chocolate Chip Zucchini Bread appears fully cooked on the outside but is still gooey on the inside, try covering the top with a piece of aluminum foil for the last 10-15 minutes of your baking time next time around. This will keep the top from getting too cooked while the inside continues to bake.  If you already took your bread out of the oven, let it cool and then discovered the gooey interior, you can still try putting it back in the oven to cook a bit more. Preheat your oven to 350 degrees, cover the top of your bread with foil and place it back in the hot oven for an additional 10 to 20 minutes until a toothpick inserted into the center comes out clean.