Can You Safely Reheat Frozen Leftovers Without Defrosting First? - Tasting Table
Briefly

Reheating frozen leftovers is safe and can be done without prior defrosting, as long as the food was cooked and frozen correctly. It's essential to heat leftovers thoroughly to 165 degrees Fahrenheit to eliminate cold spots. Different reheating methods suit various foods: microwaves and saucepans work well for liquid-based items like soups, while ovens are better for mixed ingredient dishes. However, avoid using slow cookers or other gentle heat methods, as they may keep food in a temperature range that promotes bacterial growth. Properly freezing in single servings is recommended to avoid reheating multiple times.
When it comes to reheating, you can turn to the usual suspects: The microwave, oven, or saucepan. Each one coincides with the type of food you're reheating.
Liquid-based leftovers like soups and stews do better in a saucepan or microwave in a bowl that can help them retain those flavorful juices.
While you can rest assured that reheating leftovers from frozen is perfectly safe, there are a handful of items to avoid during the reheating process...namely, slow cookers, steam tables, or chafing dishes.
Make sure you freeze your leftovers in single serving sizes because you don't want to reheat your frozen leftovers more than once.
Read at Tasting Table
[
|
]