Examination of your checks turns up Nf7, which would be a smothered mate if f7 weren't guarded by the bishop on g6. So you turn your attention to the bishop and to whether it might be captured or distracted. Notice that it also guards h7, where you have a second mating threat; in other words, the bishop is overworked. Your course is clear: play one of the threats it guards against, then the other: 1. Qxh7+, BxQ; and now 2. Nf7#.