Preheat the oven to 275°F and line a large baking tray or jelly roll pan with parchment paper.
Place the salmon in the middle of the parchment paper.
In a microwaveable bowl or measuring cup, place the butter and mince the garlic cloves into it. Heat the butter and garlic in the microwave until the butter is melted, stir to combine.
Spoon the garlic butter over the salmon and with a pastry brush, coat the salmon all over with the melted garlic butter.
Sprinkle the top of the salmon evenly with salt.
Slice the lemons into thin circles and place the lemons slices in a single layer over the top of the salmon.
Cover the salmon with foil and bake in the preheated oven for about 35-45 minutes or until the internal temperature reaches 125 degrees. It may still appear to be rare or party raw, but that is because we are using the slow roasting method which keeps it more tender. As long as it has reached a temperature of at least 120 degrees, it is fully cooked. Serve and enjoy!