According to the guidebook, this is apparently the best restaurant around here.
Literal
Guidebook [according-to-によれば], here [subj-が] this-area [at-で] most delicious shop [copula-なんだって].
~によれば 'according to' marks the information source. ここいらで 'around here / in this area' is a casual variant of この辺りで. 一番美味しい店 'the most delicious restaurant' uses the superlative 一番. なんだって combines んだ (explanatory) + って (casual hearsay quotative) — 'apparently / they say.'