This recipe was specifically designed for using fresh tortillas and letting them crisp up in the oven. I recommend following that method because the shells are way better than what you’d buy in your typical grocery store. That said, you can substitute store-bought tacos shells with an adjustment. Turn the oven down to 400 degrees instead of the 450 degrees noted in the recipe card and simply bake until the cheese melts, which should take about seven to 10 minutes. But I really do encourage the directed method — it takes so little effort and results in a much better taco.