Based on the location of the noise it can be one of two issues
1. The Steering column universal joint is sticking slightly due to it standing....
Look down near the pedals, you will see the joint where the splines insert from the column.
Although it's a sealed unit, silicon lubricant spray (DO NOT USE wd40) can help free it off... cover your pedals for safety spray liberally around the joint while turning the wheel lock to lock with the engine running for ease of turning.
Turn the engine off.
Now look down behind the engine below the brake master cylinder on the bulkhead and you should just be able to see where the column spline comes to meet the rack itself... Give that a quick spray too.
remove the bottom plastic cowling (where the ignition key inserts) and spray the height adjuster and behind the steering wheel.. Put the cowling back in place and adjust the height of the column and reach a good few times then lock it back into position...
Start the engine again and perform around ten lock to lock turns... Now take it for a drive and listen for the noise... If it cures it then great, if not then it may be a new universal joint... Nearly all cars not just Alfa's suffer from U/J issues if left standing for a long period
2. It could also be low or contaminated power steering fluid.. It should be a cherry coloured when fresh and mid brown colour at worst If it is almost black it definitely needs changing and should be changed every two years anyway.