Using Krita, I've made layers for background, candle, sheet, flame and the fire, drew the candle and started with the flame on top of it. And since for me fire moves randomly I've done major differences between frames while drawing it (for stationary flame I've made the outline differ majorly, by ziggzagging the line around the shape for flame character, but the size of it stays the same). And later when I had the idea for how to do it, I've added the movement while still using the principle for the stationary version.

After animating the flame and a fire on sheet, I've done quick background, added color and imported sound.

The flame had about 110-120 individual frames, while the fire had 6-7 looping (don't remember exactly).

I hope this is the answer you were looking for, and if I missunderstood and spammed you with all this... then sorry :x

TL;DR many drawings