Very simple, like a shepherd's meal? (4,2,3)

I believe the answer is:

easy as pie

'very simple' is the definition.
(easy as pie can mean very simple)

I don't understand the rest of the clue.

(Another definition for easy as pie that I've seen is " Really simple to do like baked dish with pastry".)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app