Amazing mold rubber in the oven

I was wondering about this myself.
Thanks for the info on baking polymer clay in silicone molds!

My family also wants to know about baking molded cookies in the food-safe silicone mold materials.

My extensive & sometimes unfortunate experience with silicone bakeware is:
1) if someone forgets the pan is silicone and turns on the broiler to crisp the top, it can survive a quick exposure to higher heat.
If you weren't there, you would never know it had been broiled.
By 3 minutes, however, the edges turn black and stay black permanently.
There was no smoke or smell at this point.

2) If you put marshmallows on top of something you're baking in silicone, and they happen to catch on fire, that will not only turn the silicone black, but make it soft and start to slump. It wasn't even as runny as molasses, more like warm wax. It took fingerprints from my oven mitts that remained after it cooled & resolidified.
I am not 100% sure it did not catch fire too, as I blew the whole pan out like birthday candles before removing it from the oven.
Marshmallow fire is not that hot, also.
I can't say if there were specific fumes from the silicone; the smoke & smell were overwhelmingly of burning sugar.

When I ran near ice-cold water over the blackened, softener silicone, it re-hardened.
It did not crack, shatter, or become stiffer or more brittle.
(I have had the same brand silicone pan crack & break when dropped from the freezer & cut through it with a butter knife from being more brittle while frozen.)
It still works as a craft mold, but I don't cook in it anymore.
The melted, blackened edge has the same flexibility and non-stick properties as the untouched bottom of the pan.
The burnt & sticky marshmallows peeled right off, for what that's worth.

My rule of thumb from overheating polymer clay is that if it turns black around the edges, I worry more about fumes and outgassing of the binding agents, and air out the oven, room, etc. Because plastic fumes can dissolve your bones over time
(way scary PBS documentary made me get a dedicated polymer clay toaster oven.)

I would not knowingly eat something out of silicone that has turned black.
We have done so with no ill effects AS FAR AS WE KNOW, but that was with the outer edges of the pan blackening and not near the food.
(Makes no difference to vapors, but we didn't find out about the broiling until washing the dishes afterward & noticed the color change.)

3) Found out afterward, we have eaten food cooked in a pan with heat-blackened edges that was washed & reused after broiling.
Apparently, it does not affect its baking performance, or the taste/outcome of food cooked in it.
I am told it may blacken easier the second time you broil it.

My concern is that because it is already permanently blackened, it is hard to tell if and when it starts to turn black(er) again.
So you'll have less or no warning that it is overheating next time.

If you can see what the silicone is doing in the oven, visible darkening or blackening along the outer & thinner edges tells you it is overheating.
Otherwise, you find out after the fact.
If someone else uses your bakeware, you might want to check for signs of abuse afterward.

Also, any kind of oil or pan-greasing can bake on as a permanent golden-brown sticky residue, just like baking in glassware.
For silicone baking pans, I dust with flour or cocoa powder instead of greasing.

If you know a colorant powder is heat-safe, that's often the only mold release I use.

I have never had an issue using craft-purposed silicone molds or bakeware with hot glue filling the mold (makes cheap clear flexible objects.)
I would easily trust it to 200 degrees Fahrenheit.

Since I am again being asked about molded cookies by braver family, I will try some salt and flour dough baked ornaments & see how non-edibles turn out first.

Silicone bakeware also transfers heat like glassware, better than metal pans, so baking time is shorter unless you bake on top of a cookie sheet, or in a water bath, to protect the bottom.
I will have to try the tinfoil trick, thanks!