I am not entirely sure where black's blunder is, but it seems like you had nice advantage somewhere out of the opening and converted quite nicely. Well played.

Yeah, Na6 is a relevant move in different lines to recapture on C5 but it was premature and you never captured on C5. Looking back, I would have played Qd2 instead of C2, took away an important square for my knight which I had initially thought of using after Na6.

Once White was firmly established in the centre - and I don't believe I have ever seen before a more powerful 'hanging pawn couple'; more often they are apt to become a liability requiring a deal of effort to maintain - Black seemed simply to have no effective defensive resources available. Wriggle he, wroggle he, the fish was in the net.

Thanks for your lovely comments everyone!