I should have written Thorbjørn Jagland as the man responsible for the prize being awarded to the EU. Apologies.
You will see that when Nobel who died in 1896 Sweden and Norway were essentially the same country.
It is unclear why Nobel wished the Peace Prize to be administered in Norway, which was ruled in union with Sweden at the time of Nobel’s death. The Norwegian Nobel Committee speculates that Nobel may have considered Norway better suited to awarding the prize, as it did not have the same militaristic traditions as Sweden. It also notes that at the end of the 19th century, the Norwegian parliament had become closely involved in the Inter-Parliamentary Union’s efforts to resolve conflicts through mediation and arbitration.
Aid from The Marshall Plan was indeed given to the whole of Western Europe by the USA at the end of the war. However it’s great success was in modernising West Germany’s devastated industrial capacity from 1945 onward.