Preheat oven to 425 degrees. Cover two baking sheets with foil and spray with cooking spray. Set aside.
Place sliced potatoes in a single layer, covering the foiled baking sheets. You may have enough slices for a third baking sheet; if so, set those aside and bake them according to the same instructions after the first set are baked.
Bake at 425 degrees for about 15-18 minutes or until potatoes are nice and crispy without being burnt. I like to rotate pans halfway through the baking time for even baking.
While potatoes are baking, prepare a large skillet with olive oil over medium-high heat. Add garlic, ground beef, and mushrooms. Stir and cook until the meat is fully cooked, which takes about 6-8 minutes. Add taco seasoning once meat is cooked, and stir to coat the blended mixture evenly. Remove from heat and place in a bowl until you're ready to serve.
To prepare the Loaded Pub Chips bar, place the crispy potatoes in a serving platter or a baking sheet lined with parchment paper. Place your choice of fixings in separate bowls. I like to gather them together in one place, like on a rimmed baking sheet. Serve immediately.