Can the sugar be replaced w/a NATURAL sweetener (not Sucralose or Aspartame)? Would granulated or powdered Monk Fruit work?

I can't WAIT to try this -I am a chocoholic (and "Team Fudgy Brownie) I live KETO for health reasons and would need to sub out the sugar. What type of NATURAL (not Sucralose or Aspartame) would be recommended? Would granulated or confectioners (powdered) Monk Fruit work? Thanks in advance!