2. Ndc2+ ..... Bxc2+
3. Kxc2 ---- (threatens mate in 1 with Bxb2#)
3. ................. d1=Q+
4. Kxd1 ....... Nf2+
5. Kc2 ......... Nd1!
The knight cannot be captured, because then it's stalemate.
7. Kc1 ......... Nd3+
8. exd3 ........ e2
9. Nc2#
On the 6th move white can also put the bishop on another square on the diagonal a1-h8.
That would be followed by:
6. Bh8 ......... Nc3
7. Kxc3 ...... b1=Q
8. Nc2+ ..... Qxc2+
9. Kxc2#!!