If you like your stuffed peppers on the softer side, boil them for about 3 minutes, then transfer to an ice bath to cool before stuffing them.
Make sure to use cooked white rice; raw rice will not bake through properly.
If you don’t have any leftover cooked rice, quickly cook up a bag of minute rice in the microwave. I’ve found a package has just about the perfect amount of rice.
If slicing the tops off your peppers and stuffing, they’ll need 45-60 minutes to bake through.