Grammar and meaning of 凝りに凝って出された


The author complains that when men cook they only put one dish (type of food)
on the table:

> なぜならその一品は、素材を選び抜いて、奮発して、時間をかけて、腕によりをかけて、 **凝りに凝って出された** 逸品なのだから。  
>  If (you ask) why that one dish, it's because it is a masterpiece in which
> he has singled out the ingredients, spent a lot of money, taken time, put
> all his skill into and ????

I can't understand the part in bold. 凝る has several meanings, none of which I
can get to fit, nor do I understand the grammar of the pattern 凝りに凝って.

Also why do we switch to passive for だす when the rest of the sentence is in
active voice?




Ａ（連用形）にＡ（活用） uses repetition of the same verb as a pattern for emphasis; the
活用 part is often seen as ～て or ～た.  

Here 凝{こ}る means to pour an inordinate amount of focus / energy into
something. To give something one's all, or to be absorbed in.

The passive is used here for 出す to change the focus from the subject (the
person making the food), to the object (the dish being made).

> なぜならその一品は、素材を選び抜いて、奮発して、時間をかけて、腕によりをかけて、凝りに凝って出された逸品なのだから。  
>

(Without context) The reason why being that the dish served is something that
he has agonized over choosing ingredients; something that he has taken time on
and poured his all into doing his best work; a masterpiece he's been
completely absorbed in.




Ａ（連用形）にＡ（活用） uses repetition of the same verb as a pattern for emphasis; the
活用 part is often seen as ～て or ～た.  

Here 凝{こ}る means to pour an inordinate amount of focus / energy into
something. To give something one's all, or to be absorbed in.

The passive is used here for 出す to change the focus from the subject (the
person making the food), to the object (the dish being made).

> なぜならその一品は、素材を選び抜いて、奮発して、時間をかけて、腕によりをかけて、凝りに凝って出された逸品なのだから。  
>

(Without context) The reason why being that the dish served is something that
he has agonized over choosing ingredients; something that he has taken time on
and poured his all into doing his best work; a masterpiece he's been
completely absorbed in.

