From Ljubomir Ljubojevic vs Joaquim Manuel Durao (1974)

Great one! I had problems with the very 1st move but when I asked myself "What the hell does black threat?", I found it! 

Just one question, 7.Qc7# is fine too, isn't it?

Of course it is :)

Don't you people think, Black's second move 2. ... Bb8 would have delayed checkmate?

Yes it would delay it but still would be losing very soon. I just gave this variation because I thought it is harder to deal with as white.

2...Bb8 3.Ba6+ Kc7 4.Qb7+ Kd8 5.Qxb8+ Bc8 6.Bc5 is easier to find since they are natural moves imo.

@indianteacher, you seem to be right though the end result doesn't change.

2. ... Bb8 3. Ba6+ Kc7 4. Qb7+ Kd8 5. Qxb8+ Bc8, after which black can only delay.

7.Qc7# was another option.

Nice puzzle! 

I enjoyed this puzzle, also tried to mate on c7 at the end there

nice indeed