I have no idea of any classed near Velachery.
But I can suggest you one near Madhavaram Milk Colony, Tamilnadu Palm Products Development Board.
My wife had completed many courses there other than Chocolates and she is very good in prearing Home made chocolates, Home made cookies, Bread, Bun, Cakes, Pickles, Squash for Aereated drinks and lot more.
Calles starts from June, it may be long from your place, but it is worth doing a course there & upon completion of the course you are eligible for Central Gov..Loan & for ladies from 25& - 35% of their loan amount is waived.
All the best.