Russian Nesting Quine
Underload, 4 bytes
N=1: Try it online.
 ()S

N=2: Try it online.
 ( ()S)S

N=3: Try it online.
 ( ( ()S)S)S

Explanation:
Self-explanatory, but I add it anyway.

(...)S prints anything between the parenthesis to STDOUT
The space before it is a no-op to make the byte-count even and comply to the rules of the challenge.