How to go about asking my boss for a letter of recommendation?

You don't you put the company down as a reference and if you get the job they will contavt them

You could use a friend/coworker as a reference instead of your boss. That is acceptable. But if you really want to use your boss, here is how I handled that in the past. I was at a job where I knew I was at a dead end. So I went to my boss and told him what my career and salary goals for the next 2 years were. He told me that was unattainable where I currently was. Then I told him that I already figured that out, so I'm going to have to find another job.

It worked out really well for the both of us. I used him as a reference, and was able to go interviewing without sneaking around. And I was able to help them select a replacement and train them. It made for a smooth transition.

Talk to your boss (don't mention the job yet unless they ask) and ask for a recommendation letter.

Do what you have to do, if you have to move on then he should let you go.

No one is indispensable, they will find some one to replace you.

When you're ready to leave give your boss 2 weeks notice and a resignation letter.

maybe you can go ahead and ask him, tell him the reason why you quit and what you worried about

Did the company ask for a letter of recommendation?

It is very rare for companies to request LOR these days because they can so easily be falsified.

Would you like me to write one for you. I can make it look like your employer wrote it, including adding their signature.

Just ask him if and only if this new company has OFFERED you the position on the proviso of a good letter of reccomendation or reference.

Tell him this new job offers twice as much money and weekends off, no sane normal boss minds people moving on. It is part and parcel of employing people, especially when this new job is a position with better pay and conditions.