So this is what I did:
1. gather the stuff you need: pillow contents, metal washers, red & black spray paint, red & yellow paint and some PVA glue
2. Tear the pillow contents to suitable pieces and spray them with red
3. Glue them on metal washers
4. Paint them starting with red and working your way via orange to yellow. No need to try to cover everything with the paint, just brush it with a broad brush here and there
5. Paint the washer red
6. Spray the from rather far with black spray to present black smoke, with the fire still showing beneath it - I run out of black spray, so I will add more to my flames once I get more.
Very fast, very easy. Good results!
Same in pictures:
I also pushed the brush inside the material to get paint there
Ready for the black spray
More black spray still needed...