、。
When it comes to cooking, nobody can match Mary.
Literal
Cooking [quotative-と] say matter [conditional-になれば], nobody Mary [to-には] can't-match.
誰も + negative verb creates universal negation — 'nobody does X.' ~ということになれば is a somewhat formal conditional meaning 'if it comes to the matter of X.' にはかなわない (can't match) takes には to mark the person being compared against; かなう means to match or rival, and its negative form expresses inferiority.