The English phrase '12:35' translates into Spanish as 'doce trienta y cinco'.
If you wished to say it was 12:35 in the afternoon in Spanish, you would say: 'doce treinta y cinco de la tarde en la tarde.'
If it was 12:35 in the morning, you would say in Spanish: Doce treinta y cinco de la tarde en la manana.'
To say it a little differently, you could try 'cinco y cuarenta minutos despues de las doce de la noche', which means 'five and twenty minutes to one.'
If you didn't wish to be so accurate, you could simply say 'es solo pasado doce hasta treinta' which means 'it is just past twelve-thirty'
Learn more about telling the time in Spanish with this film: