Burnt parchment paper is not toxic. However, the fumes it releases as it is burning are toxic when inhaled. In addition, there is the danger of the silicone film of the parchment paper catching fire so it is important to keep the paper away from open flames.
Baking Paper Burnt into Ashes in The Oven; Food Safe for Consumption?
If you wouldn’t mind the taste, I’d say go for it.
Carbonized (charred) organic materials, such as char-broiled burgers, steaks, etc. are typically reported to have some carcinogens. But we eat them anyway.
Plus, I’m not sure how you managed to set it on fire unless perhaps something started burning in there like a grease fire flareup or something, but the food on the paper should be fine for consumption outside of taste (just so long as you don’t make a habit of it.)
I’d also recommend you keep the photo so that if it happens again, you would be able to write to the company to inform them of what’s going on. Who knows…It could save someone’s house from burning down if they need to recall.
Lastly, if you ever have a fire in your oven, you should keep it closed because those things are designed to withstand and contain heat. Opening the oven literally fans the flames and gives them an opportunity to escape the oven.
ALSO SEE: Is Parchment Paper Safe in Microwave?
Is Silicone Parchment Paper Safe?
Parchment paper is made with food-safe materials so it is safe to consume, accidentally.
Is Baking Paper Toxic?
Not at all. Bleached parchment paper is 100% safe to cook with.