For this guide you will only need a knife, no skills are required. Once you have the knife, head over to the Grand Exchange and buy as many Chocolate Bars as you want / can afford. Once you have the chocolate bars, go ahead and bank them and fill up your inventory with them. Right click and choose to powder all the chocolate.
Once the chocolate has been powdered into Chocolate dust you can resell them on the Grand Exchange. You will be making about a 60gp profit from each bar of chocolate turned into Chocolate dust. So 1000 bars gives a 60k profit. You can make around 200 – 300k gold in an hour of doing this.