Now this is where it gets technical, (not really). You screw the cap on nice and tight and submerge the whole bottle in warm water. That's warm
water... not too hot, and not too cold. Think Baby
's bottle warm.
Then you have to leave it for a few hours to allow the toffee's to slowly dissolve. I check every hour or so to make sure the water hasn't gone cold and top up with hot accordingly.