I'm sauteeing pierogies for a group. Can I safely keep them warm in the oven for 6-7 hours?

Serving food to a crowd safely is important. I would recommend cooking the pierogies ahead of time and freezing. Keep them frozen until you heat them in the oven. They should only be kept in the oven for an hour. After an hour, they will start to deteriorate. Here are a couple of food safety tips:

Place containers of cold foods in crushed ice to keep them below 40 degrees Fahrenheit.

Hot or cold foods should not stand at room temperature for more than 2 hours. If in doubt, toss it!

Here are more Tips for Freezing and Reheating Foods. Have a fabulous event!