I don't see a problem with simple materialism here. Nf7, forking 2 rooks.
Another option is d5, attacking the Knight (which is guarding b8) and opening up the diagonal for the White Bishop. If he takes back with the Pawn, Qxf5 mandates a response of ...Rd7 and allows Bxa7.
Personally I'd take the Rook with a Knight before continuing to pound the Black King.
What follows is a clip from a game I played with the computer (on hard). I was really proud of the position I was able to obtain.