The secret to this recipe is the way you build it. You have to layer the criss-cut fries, starting with the largest on the bottom, using the cheese sauce between the layers to hold the pyramid together as you build it. It's also very important that the cheese sauce be the right consistency — too thin and it won’t hold together, too thick and the texture won't be right.
Fill a deep pot no more than 1/3 full with oil and heat to 350 degrees. Add the fries in batches and fry until hot and golden brown, about 3 minutes. Drain and transfer into a clean stainless steel bowl. Season immediately with kosher salt, to taste.
Place about half of the fries on a plate and top with 1 ounce of the cheese sauce. Arrange the remaining fries in a tall pile. Drizzle the remaining cheese sauce evenly over the fries. Top with the bacon. Drizzle the ranch dressing in a criss-cross pattern over the fries. Scatter the chopped scallion over the fries.