In a large skillet over medium heat, brown the ground beef until fully cooked, breaking it apart with a spatula. Drain excess fat if necessary.
Stir in the chili powder, cumin, garlic powder, onion powder, salt, and pepper. Cook for an additional 2-3 minutes until the spices are fragrant and well combined.
While the beef is cooking, prepare the tostada shells according to package instructions or bake them in a preheated oven at 400°F for about 5-7 minutes until crispy.
To assemble, spread a layer of refried beans on each tostada shell.
Top with a generous portion of the seasoned ground beef.
Add shredded lettuce, diced tomatoes, and shredded cheddar cheese on top.
Finish with a dollop of sour cream and jalapeños if desired.
Garnish with fresh cilantro before serving.