Answer:
; (semicolon)
Step-by-step explanation:
The use of adjunctive adverbs, such as however, is to connect two independent clauses and form only one sentence. They are placed between a semicolon (;) and a comma (,). This is done in order to simplify speech and get ideas across in a clearer way.
The two sentences that are connected in this case are "Everyone knows he is the best cook" and "he refused to enter the contest".