We all know how strong Raul Capablanca was from 1910 onwards. Master Joseph Henry Blake won him in 1911 in London in a game of simultaneous with the following variant:

1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3 f5 5. ef5 Qf6



This variant seems to be taken from the trunk of the memories where the black king plays as if it were a major piece and is solving all the problems posed by the great Capa in the center of the board.
As for the opening that calls us, it strikes me that there are very few games in the database with the bizarre play 5 ... Qf6.
that is more a surprise variant. Most recommended is the main line 5...e4.
I attach the pgn file of the mentioned item along with the compilation of other items along the same path.

Best wishes,
Marco.