Reheating Frozen Brocolli Fritters
In a comment, you say that you were told to bake the fritters rather than frying them. That implies that they're already cooked, and just need to be reheated.

A fan-assisted oven would be ideal for this, but a regular oven will work too. Put the fritters, still frozen, on a baking sheet or metal baking pan in the middle of the oven. Assuming the fritters are around 1/2 inch thick, 15 minutes at 200C (400F) in a regular oven or at 180C (350F) in a fan-assisted oven should suffice. (As with any cooking instructions, preheat the oven to the specified temperature unless you're told otherwise.) Flip them halfway through cooking. By the time they're done, you'll likely see a small amount of bubbling at the surface, even in the center.

An easy way to check whether a food has come up to temperature is to stab it straight through the middle with a metal fork. Let the fork sit in there for a few seconds, then put the part of the fork tines which were in the middle of the food just in front of your closed lips. If you can't feel heat radiating off them, then gently touch them to your lips. That should give you an idea of how much the food has warmed.