Is this possible..............?!

Best Answer - Chosen by Voters

Don't bake plastic - it could melt or release nasty chemicals into your cake.

Use a sharp knife to cut a slit in the bottom of the cake, fold your message up and push it into the hole.

I suppose you could but don't use plastic! It will melt and most likely poison or choke you.
Use parchment paper which is suitable for baking. Use a sharpie pen so that color does not fade. Roll like a cigarette and insert in middle of cake.

Good luck.

Susan is correct. You could bake a layer cake, then place the package in between the layers when your frosting it..

Bake the cake. Make a slit or small hole in the cake. Insert paper, and then frost.