Preheat the oven to 200°C, or 180°C fan forced.
Wash and thoroughly dry the potatoes. Pierce them several times with a fork.
Rub the skins with melted beef tallow and season with salt.
Roast for 60–75 minutes, until the skins are crisp and the centres are tender.
Meanwhile, melt the remaining tablespoon of beef tallow in a large saucepan.
Add the onion and jalapeños and cook for approximately 5 minutes until softened.
Add the beef mince, season with salt and cracked black pepper, and cook until properly browned.
Add the garlic, tomato paste and chilli spice mix. Stir for 1–2 minutes until fragrant.
Add the crushed tomatoes, kidney beans, beef stock, Worcestershire sauce and brown sugar.
Simmer uncovered for 30–40 minutes, stirring occasionally, until the chilli becomes thick and rich.
Stir in the dark chocolate during the final 5 minutes. Taste and adjust the salt and pepper.
Cut open the roasted potatoes and fluff the centres with a fork.
Add butter to each potato and season the potato flesh properly with salt and cracked black pepper.
Spoon the chilli generously over and into each potato.
Top with the tasty cheese and mozzarella, then return to the oven for 8–10 minutes, until melted and bubbling.
Finish with sour cream, jalapeños, freshly chopped spring onion or chives.