That is an impossibility though - you cannot have a stronger Europe within NATO, because if you do then the argument for NATO (as an American shield to protect Europe) is removed; Europe is already strong enough to not need it.
The EU urgently needs to example what it wants to be and, if ever closer union is the aim (and it should be) then it needs to establish the means by which it can defend itself without any US involvement. That means pan-EU armed forces and a pan-EU foreign policy. Doing that will considerably boost security here and worldwide. Relying on the current version of NATO will just result in its demise.
I disagree. NATO as a defensive entity has the structure, governance and command and control elements already in place. Its structure, training command and control functions are already stress tested and functional with close cooperation between allied states.
The thing needs to change is for European nations to take more responsibility for their own patch. They need to increase funding, increase weapons and ammunition manufacturing and improve on logistics and increase war storage. The US will and should always be there but in a slightly diluted role within Europe.
Moving to a completely new EU force would IMO be a disaster. You would need to start from the ground up. War-fighting capabilities, C2/3/4 functionalities, comms , Intel, logistics would all need to be started from scratch. It could take 15 years for that kind of force to become fully combat capable.
I think we’re all acutely aware that the focus of the US going forward will be China and because of that European NATO states need to take up the slack (starting now).