Preheat oven to 220 degrees C. Place the bacon in a baking tray and cook in the preheated oven for 30 minutes.
Meanwhile, cook spaghetti according to package instructions.
During the last ten minutes of cooking the bacon, take tin out of the oven and sprinkle pine nuts over the bacon slices. Put the tin back to oven for the remaining 10 minutes.
When bacon is browned and crisp, take the tray out of the oven, add the drained spaghetti to the tray and toss thoroughly. Add the cheese and season with sea salt and black pepper. To serve, sprinkle with the tarragon and lemon juice.