After some confusion in the comments, I think I have an answer for you. There are three main methods for making a meringue and two main methods of cooking them.
First we have a French meringue, which is what you've made before.
Second, we have Swiss meringue. Here the egg whites and sugar are gently heated over a water bath stirring constantly until the mixture reaches a temperature of 79 degrees Celsius. At this point you transfer the mixture to a mixing bowl and whisk until cooled.
Finally, an Italian meringue is made by whisking a hot simple syrup into the eggs whites.
The different methods of preparation have slightly different outcomes. A French meringue tends to be more fragile before cooking and the end result is lighter. A Swiss or Italian meringue has more volume and tends to be more stable before cooking and have a more marshmallowy/chewy end result.
All these meringue types can be cooked either slowly in the oven as you describe, or toasted. The slow oven cook will produce a meringue that's hard on the outside and either fluffy or chewy on the inside. This is used to make for example Pavlovas or meringue cookies.
For a pie topping, you instead simply pile the meringue on top of the pie and torch it with a blowtorch or (place it in the oven on 'grill') until the top is your desired level of toasted. This takes at most a few minutes. Toasting can be done with any merigue, although Swiss and Italian are preferred, since the egg white has been heated to safe temperatures already. If you toast a French meringue, you are serving mostly raw egg white and need to take appropriate precautions to avoid salmonella.