Recommend

Both the verb 'to recommend' and the related noun recommendation are among the 117 mis-spellings listed as 'Common difficulties' in the section on 'Spelling' within 'Writing' in UEfAP.

The common spelling problem with recommend is to decide which consonant to double.

There is a double '-m-'.
    
The '-c-' is single.

• The same is true of all the forms of the verb, recommended, recommending and recommends, and words derived from it like recommendation and recommender. The spelling is that of its root, commend.