Add the olive oil, chili powder and cumin to a large cast-iron pan over medium heat. Toast and stir until the spices are fragrant, about 2 minutes. Add the beef, salt and a few grinds of black pepper and cook, breaking the beef into bits while browning, until fully cooked, 8 to 10 minutes. Add the marinara sauce and stir to coat. Add the pasta straight from the bag and stir.
Level the contents of the pan and top with the cheese, then arrange the jalapeno slices around the pan on top. Bake or grill with the lid closed until the cheese melts and is golden on the edges, 10 to 15 minutes. Top with the Greek yogurt and scallions. Serve warm.