Spray a large nonstick skillet with nonstick spray and set over medium-high heat. Add the bacon and cook until crisp, 3 to 4 minutes. Remove the bacon from the skillet, keeping the drippings in the skillet. Remove the skillet from the heat. Chop the bacon and reserve.
Place the potatoes and garlic in a large pot with enough water to cover by 2 inches and bring to a boil. Reduce the heat and simmer until fork-tender, about 20 minutes. Drain. Return the potatoes and garlic to the pot. Mash with the broth, yogurt, salt and pepper until smooth. Stir in 1/2 cup panko, the cheese, scallions and reserved bacon. Shape into eight 3-inch patties. Place the remaining 3/4 cup panko in a shallow dish and dredge the patties in the crumbs.
Heat the bacon drippings over medium-high heat. Add half the potato cakes and cook until browned and crisp, 3 to 4 minutes per side. Carefully transfer to a serving platter. Repeat with the potato cakes. Serve hot.