Cook bacon and get nice and crispy. Remove to a paper towel-lined plate to drain.
Dispose of the majority of bacon grease, leaving a little in the pan. Add the garlic and a pinach of salt to the pan and cook 30 seconds until fragrant.
Add the 4 cups of spinach to the pan and sautee until wilted. It may not all fit in the pan all at once, so you can start with 1 or two cups and add the remaining spinach as the others begin to wilt. Remove to a plate.
Season salmon filet with salt and pepper. Add a splash of olive oil to the pan, and add the salmon filet, skin side up. Cook for 6 minutes, then flip and cook for 4 minutes on the other side.
Remove salmon to serving plate. Top each filet with sauteed spinach, and ladle lemon butter sauce over top. Sprinkle with blue cheese and crumbled bacon and serve warm.