I couldn't find tostada, or taco shells, at the supermarket the day I went, but I had some corn tortillas in the freezer. As you can see, I placed two in a small ramekin, then baked at 375 degrees for about 15 minutes to crisp them up. They were alright in a jam but I would still recommend buying the shells. And if you can't find the nacho cheese soup (I couldn't), cheddar cheese soup works just fine.
Makes 10 servings
2 pounds lean ground beef
2 (1.25-ounce) envelopes taco seasoning mix
1 (16-ounce) can refried beans
1 (10.75-ounce) can condensed fiesta nacho cheese soup
1 (10 count) package tostada shells
toppings such as shredded lettuce, chopped tomatoes, shredded cheese, sour cream, etc.
Cook the ground beef in a large skillet over medium heat until browned. Drain off fat, add taco seasoning and cook according to package directions.
Transfer meat to 3 1/2-4 quart slow cooker. Stir in beans and soup.
Cover and cook on low heat setting for 3 to 4 hours or high heat setting for 1 1/2-2 hours. Serve on tostada shells and top with ingredients on choice.