Pre-heat your oven to 425 degrees. Line a baking sheet (or two, depending on how many you are cooking at once) with aluminum foil and mist the aluminum foil with cooking spray.
Lightly mist a large skillet with cooking spray and bring over medium-high heat. When hot, add the ground beef and cook, stirring occasionally and breaking up into small chunks with a cooking spatula, for 5-6 minutes until browned. Drain any liquid if present. Add the taco seasoning and water and stir into the meat until well combined. Once the mixture is bubbling, reduce the heat to low and simmer, stirring occasionally, for about 3 minutes until the liquid is mostly absorbed into sauce.
While the meat is cooking, place the contents of the can of refried beans into a mixing bowl and microwave for 30-60 seconds until softened. Add the salsa, queso blanco, and shredded cheese. Once the meat is finished cooking, transfer the saucy meat to the mixing bowl and stir everything together until well combined.
Lightly mist a skillet or griddle pan with cooking spray and bring over med-low heat. Depending on the size of your pan, you can heat the tortillas one at a time, or several at a time. *Place the tortilla(s) on the heated pan and cook for 30 seconds. Flip the tortilla and cook for another 30 seconds until pliable. Repeat with all 21 tortillas. *You may want to work in batches. I would heat up 4-5 tortillas, fill them, then heat up 4-5 more, fill them, and so on.
To fill each taco, take one of the softened tortillas and lightly mist one side with cooking spray. Place on a clean surface like a cutting mat, sprayed side down. Add three tablespoons of the beef and bean mixture to one half of the tortilla surface and then spread into an even layer. Fold the bare half of the tortilla over the side with filling and gently press down to stick. Transfer to the prepared baking sheet from step one. Repeat with remaining ingredients to make 21 tacos.
When ready to bake, place the baking sheet(s) of tacos into the heated oven and bake for 12-15 minutes, flipping the tacos over about halfway through. Serve with your favorite taco toppings.