Command Atlantic, December 1943.

[Nick Beale]

Originally Posted by Chris Goss

Nick Beale will no doubt have this chapter and verse

This coming from the man who literally wrote the book!
From Air Operational Watch reports in National Archives HW 13/37:

24 December: 8 sorties by 1./128 from Brest (Fw 190s) and 14 by Ju 88s of I./ZG 1; from KG 40, 6 He 177s and 9 Fw 200s; 1 Ju 88 heard between 2115 and 2310 BST, thought to be Kdo. Kunkel night fighter; 1 Ju 88 of 1.(F)/123 on reconnaissance.

25 December: 7 Fw 200s up from 1030 BST, staying in the air for 12 hours. "Escort to the blockade-runner Osorno reported at 0414/25 continuous bombing, and requested fighters from first light. Continuous fighter escort was not possible due to the situation with reard to forces available, but the following were to operate: 14 Ju 88s up at about 1100, 10 Ju 88s up at 1445 … returning 1830 … Close escort by Fw 190s was also intended for the ships as soon as they should come within s/e fighter range, which was expected to be about 1500."

26 December: Bf 109s to cover the Gironde Estuary for the arrival of Osorno.

27 December: reconniassance for Alsterufer started on the 26th and continued on the 27th but the Allies don't seem ot have detected any Ju 88 fighter activity. However the reports says: A ship tought to be Alsterufer was sighted by Coastal Comman at 1030 in 46º 50' N, 19º 29' W, course East, 15 knots and was shadowed. At about 1700 a Liberator of 311 Squadron made an attack evidently on this ship and has reported that the ship was set on fire and sank, about 70 survivors seen in 4 lifeboats.
28 December: reconnaissance for the blockade runner carried on so it seems the Germans didn't know it had been sunk.

On 3 December, Flifü Atlantik had 16 (7) Fw 200s; 26 (11) He 177s; 64 (32) Ju 88 fighters; 9 (6) Fw 190s. For reconnaissance 7 (3) Ju 290s and 9 (2) Ju 88s. Kdo. Kunkel had 7 (0) Ju 88 night fighters.

If you want more from the German side you can get the Kriegsmarine diary for December 1943 here: https://opus4.kobv.de/opus4-zmsbw/so...s/id/1/rows/10
Each month can be downloaded in pdf format and is searchable, so you can just search for Osorno and Altersufer and see what comes up.