You may study termination clause in your appointment letter. The notice period and notice pay option @ basic/gross pay should have been mentioned. It shall be appropriate to inform say 7 days in advance that you should be resigning on date.................and within this period you shall cooperate to finish all tasks, knowledge transfer, training of replacement etc. Deposit the company property under proper acknowledgment.
You can tender notice pay for the balance period of your notice by cheque or you can ask the company to adjust in your F&F. In the same written communication(under acknowledgment) you can demand to issue acknowledgment of your resignation, acceptance of your resignation, and to keep settlement of your a/c,F&F, form 16,PF accumulation reports, PF withdrawal/transfer forms, service certificate, relieving certificate, NOC/NDC etc
Your boss is doing so since he has not been able to find the replacement. As an able leader he and company including HR should look beyond their problems and find solution and give the departing employee a smooth exit. You should remain cool, gentle, amiable, and use your persistence, persuasion, reasoning, negotiation skills and leave with a happy note.