Possibly building an enclosure over a spawner in peaceful if you don't mind switching over, allow an opening for a door get a bow and shoot Em although personally best way for me to take them down is portion of fire resistance so you don't catch on fire which is where most of your damage comes from.
When I find a blaze spawner room, I first patch over the ceiling if it's an open-air room (fire resistance potion may be necessary for this), and then I add a couple of blocks around the front and an iron door (with a lever to control it, but maybe a pressure plate would be nice too). Then I cheaply stand outside the door and whack their little dangly bits while they're trying to come down the stairs to get to the door. I don't usually get too crispy. The door is a failsafe in case I get overrun.
How to make blaze traps?