Use my double-coating technique when breading the mozzarella sticks. Dip each stick first in flour, then in beaten egg, and finally in breadcrumbs. Repeat the egg and breadcrumb coating step to create a thicker breading layer, which helps to seal the cheese inside. Before cooking, freeze the mozzarella sticks for at least 30 minutes to 1 hour. This helps solidify the cheese inside and prevents it from melting too quickly during frying or baking. Also, be sure to fry the mozzarella sticks in small batches to prevent overcrowding in the fryer, which can lead to uneven cooking and possible bursting.