Step 1

Preheat the oven to 450 F (230 C) for 30 minutes (please use an oven thermometer for accuracy; the correct temperature is essential for a high-rise). Adjust your oven rack to the position just below center. Place a 6-cup non-stick popover pan inside to heat up.

Step 2

In a small saucepan (or microwave), gently warm the milk and butter over low heat.

Step 3

Crack the eggs into a large bowl. Add the sourdough starter, mustard, parsley, garlic powder, salt and a few turns of freshly ground black pepper. Whisk to combine.

Step 4

Gradually pour the warm milk mixture into the egg mixture while whisking continuously.

Step 5

Add the flour, and continue to whisk until the batter becomes thin, frothy and lump free. It should be warm to the touch. At this point, pour the batter into a measuring jug if you have one, or use a ladle for portioning.

Step 6

Remove the hot popover pan from the oven. Generously coat the inside and surface of the pan with cooking spray.

Step 7

Pour/ladle the batter into the pan, filling each cup about 2/3- 3/4 full. It will sizzle.

Step 8

Place the pan into the oven. Reduce the heat to 400 F (200 C). Bake for 35-40 minutes. DO NOT OPEN THE OVEN DOOR while the popovers bake. They will be beautifully risen and deep golden brown when ready.

Step 9

Serve piping hot.