A 1944 Norway invasion would hinge on Trondheim and Narvik

How would you plan an Allied invasion of Norway in 1944?

Seize Trondheim and Narvik, establish a northern front, and bring enough carriers and surface firepower to dominate the narrow approaches before advancing south with Norwegian forces.

This counterfactual identifies Trondheim as the operational key and pairs it with a landing at Narvik to establish a northern front. Approaching Trondheim through a narrow fjord would demand overwhelming local firepower, perhaps three or four fleet carriers plus battleships and Norwegian support. The answer exposes the geographic and air-power constraints behind a seemingly simple amphibious proposal.