Hello Margaret,
To heat a standard individual chilled savoury pie (weighing roughly 150g to 200g) thoroughly in an 800W microwave, you should heat it on Full Power (100% / 800W) for 2 minutes to 2 minutes and 30 seconds.
Before you begin, please ensure that you completely remove the pie from any packaging, particularly any aluminium foil tray, as metal cannot go into a microwave. Transfer the pie onto a microwave-safe ceramic or glass plate.
Microwave on full power for 2 minutes. Once the timer finishes, check that the centre of the pie is piping hot by carefully inserting a skewer or the tip of a knife into the middle. If it needs a little more heat, continue warming in short 30-second bursts.
After heating, let the pie stand for 1 to 2 minutes. This standing time is very important with microwaves, as it allows the heat to equalize throughout the dense filling and prevents cold spots in the centre.
As a quick chef tip: if you wish to avoid soggy pastry, you can microwave the pie for 1 minute and 30 seconds to heat the centre quickly, then finish it in a preheated conventional oven at 180°C for 4 to 5 minutes to crisp up the crust.
