In a large skillet over medium heat, cook the ground beef until browned, about 5-7 minutes. Drain excess fat if necessary.
Stir in chili powder, cumin, garlic powder, onion powder, salt, and pepper. Cook for an additional 2-3 minutes until the spices are fragrant.
While the beef is cooking, prepare the tostada shells according to package instructions, usually by baking or frying until crispy.
Spread a layer of refried beans on each tostada shell.
Top each tostada with a generous portion of the seasoned ground beef.
Add shredded lettuce, diced tomatoes, and shredded cheddar cheese on top of the beef.
Finish with a dollop of sour cream and jalapeño slices if desired.
Garnish with fresh cilantro before serving.