In a large skillet, cook the bacon over medium heat, turning halfway through, until just crisp, 8 to 10 minutes; drain on a paper towel-lined plate. Discard all but 2 tablespoons of the bacon grease from the skillet.
Return the skillet to medium-high heat, add the potatoes and cook, stirring occasionally, until golden, 6 to 8 minutes. Stir in the onion and cook until softened, about 5 minutes. Stir in the beans, chicken broth and lemon juice; season with salt and pepper. Simmer until the liquid is almost absorbed, about 7 minutes. Stir in the spinach and cook until just wilted, about 1 minute. Crumble the bacon on top and sprinkle with the scallions and parmesan.