Place a rather large pot on over medium heat and add in the olive oil. Next, add in onion and garlic and allow to brown, stirring occasionally. The chilli pepper next, remembering to stir so nothing burns. You can remove the chili pepper if you don't want it to be too spicy, or you can remove the seeds before you add it to the pot.
Toss the beef in and allow it to brown, again stirring occasionally. Once the beef is browned and mixed with the onion, garlic and chilli add in the paprika, cumin, cayenne and cocoa powder and stir, allowing it to cook about a minute before adding in the tomatoes and paste. Mix well.
Bring the pot to a boil, reduce to a simmer (just at or under medium heat) cover and allow to stew for at the very least an hour, but I'd let it cook a couple of hours, stirring occasionally to keep it from sticking and adding water as it cooks to keep it wet like a stew but not drowning like a soup. The longer it cooks or sits, the more the flavors meld and the better it tastes (second day chilli is always better!).
Salt and pepper should be added about 10 minutes before you plan to eat, this will keep it from being too salty as the water evaporates.
Chili Stuffed Bell Peppers
Take a knife and insert it into the top of the pepper, cutting around the stem and remove it. Wash out the little seeds and drain the water from the pepper as you prep the other peppers.Place the peppers on a baking sheet with the hole up.
Spoon in the chilli until it reaches the top of the pepper, top with a cheese slice or shredded cheese. Rinse and repeat until all of your peppers are done. Bake in a preheated oven at 350F (180C) for about 20-30 minutes. Remove and allow to cool slightly before serving.