The cook time includes cooking the ground beef.
I always add black beans to the ground beef seasoned with taco spice mix. You can also layer them separately. This recipe also works great with shredded cooked chicken (see my Slow Cooker Mexican chicken recipe) or ground turkey.
For easy clean up, line the sheet pan with parchment paper. I do not recommend aluminum foil as it can rip and come off with the food. I used a 13" x 9" pan for this recipe. I had leftover ground beef that can be used for tacos later.