I feel there has been some confusion in the move order to Markovich variation:
I too consider this a riskfree way for white to play for a win, but some care is needed:
1.e4,e5 2.Nf3,Nc6 3.Bb5, f5 4.Nc3, fxe 5.Nxe4,d5 6.Nxe5,dxe4 7.Nxc6,Qg5 8.Qe2,Nf6
9.Nxa7+, Bd7
r3kb1r/Nppb2pp/5n2/1B4q1/4p3/8/PPPPQPPP/R1B1K2R w KQkq -
Now Markovich gives the remarkeble variantion 10.f4, Qc5 11.Nb5 (or is it 11.Nxb5 !?

)
overlooking 11.Nxb5,Bxb5 -+ and black has won two pieces in one move.
The timing of the capture on d7 may be important:
I. 10.f4?! followed by Bxd7+
II 10.Bxd7+! at once variation I. 10.f4,Qc5 11.Bxd7+, Kxd7 and now white runs into trouble if he follows the Markovich plan:
12.Nb5 (12.Qb5+,Kd6!)
12....,Qxc2 13.d4,Bb4+ 14.Kf2 And now black doesnt have to play
14....Qxe2?!.
14......e3+! is an intermediate move that is possible because of the threats Re8+/Ng4+
15.Kf1,Qf5 and black has an good game.
variation II. 10.Bxd7+! 10.Bxd7+,........ 10.........., Nxd7 (Now 10....
Kxd7 11.Qxb5+ with a won endgame)
11.f4!
11.........., Qc5 (11...Qxf4 12.d4!, Qf5 13.Nb5 0-0-0 14.Rf1! +- (Orlando-Lanzani 1991)
12.Nb5, Qxc2 And now white has two ways to enter a pleasant endgame
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13. Nc3!?, 0-0-0 14.Qxe4 (Kovalevskaya-Kryukova, 2002)
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13. d4! , Bb4+ 14.Kf1/f2, Qxe2 15.Kxe2 (Pilgaard-Simonsen 2003)
My conclusion is that white should first take on d7
and his next move should depend on how blacktakes back:
(a) knight takes back: only then 11.f4!
(b) king takes back: exchange queens with Qb5 The reason is that if white inserts 10.f4 Qc5 , black can take on d7 with his king without being
forced to trade queens on b5.