Place the scallops on one of the paper towel-lined plates and pat with another paper towel to dry thoroughly. Season them generously with kosher salt and pepper and set aside.
Place a large, heavy skillet over medium heat. Add the bacon and cook until crisp, turning to brown both sides. Remove the bacon to the second paper towel-lined plates to drain.
Remove the pan from the heat and drain off excess drippings, leaving a thin coating in the pan. Place the pan over medium-high heat.
When the drippings are hot, place the scallops in the pan. Let the scallops cook for about 2 to 3 minutes on each side.
Remove the scallops to a warm plate or tray and keep them warm.
Reduce the heat to medium and add the shallots to the pan; cook, stirring, until they are softened, about 2 minutes. Add the garlic and cook for 2 minutes longer.
Add the spinach, a handful at a time, until it is all in the pan; season with salt and pepper and cook until it is wilted, about 2 minutes.
Arrange the spinach on a serving dish and top with the scallops.
Crumble the drained bacon and sprinkle it over the scallops and spinach.