I must be doing something very wrong because my first 2 simple attempts, warming a croissant, were failures.  I used to warm a croissant in a regular oven at 300 degrees.  In the toaster oven I used the same temperature.  First I put the croissant on the top rack and the top was very burned.  The next day I put the croissant on the bottom rack and the bottom was VERY burned.  I am now very hesitant to put meat  or fish in the oven for fear of a repeat.  I will keep trying but am not a fan so far.