Preheat the oven to 400 degrees F. Place a cooling rack on a rimmed baking sheet. Top with a 12-by-10-inch piece of parchment.
Arrange the bacon slices horizontally on the parchment so they are overlapping to form a large rectangle the size of the paper. Bake until the bacon starts to shrink and render fat, about 20 minutes. Set aside to cool slightly. Increase the oven temperature to 450 degrees F.
Meanwhile, bring a small saucepan of salted water to boil. Drop the green beans in the water and cook for 2 minutes, then remove to a strainer and run a little cold water over the beans to cool.
To assemble the roulade, spread the potatoes on the bacon blanket in a 6-by-10-inch rectangle, leaving a border of uncovered bacon on all sides. With the back of a spoon, make 2 long troughs lengthwise down the center of the potatoes, leaving space between and around the troughs. Spoon the gravy into the troughs (keeping the gravy chilled prevents it from running all over the potatoes). Sprinkle the gravy and potatoes with the Cheddar. Arrange the green beans 2 to 3 across in a thin line on top of the Cheddar, in between the gravy troughs. Sprinkle the Parmesan over the green beans and potatoes.
Form the stuffing into a 10-inch log; you can use your hands to shape it or spoon the stuffing onto a piece of parchment and tightly roll it into a log. Place the stuffing log down the center of the bacon rectangle. Working from one of the long sides of the bacon rectangle, grab the parchment and pull it up and over the stuffing. Use the parchment to help you roll it into a roulade, making sure it ends up seam-side down.
Bake the roulade until the bacon is cooked and crispy, about 30 minutes. Let rest for about 5 minutes, then transfer to a cutting board and slice into 1-inch slices. Serve with warm gravy and cranberry sauce.