Combine the starter with the flour into a bit of a paste in a large mixing bowl.
Mix in the spelt flour, milk and golden caster sugar. Whisk until everything is properly incorporated.
Cover the mixing bowl with a damp tea towel and leave in a warm place for at least 4 hours. I usually leave mine overnight so I can make them for breakfast. See notes for additional suggestions. It should be slightly bubbly when it's ready to use.
Heat a frying pan or skillet over a medium heat.
While the pan is heating up, mix the baking powder through the batter
Lightly oil the pan, making sure it coats the surface.
Add a small ladleful of batter to the hot pan, spreading it to about a 10cm circle.
This is quite a bubbly mixture, so the usual trick of watching for bubbles may not work, but keep an eye on the middle of the pancake and check the underside. Once it's browned you should be able to flip it. In a hot pan I was getting around 1 minute per side.
Flip and cook the other side. Transfer to a pancake and keep warm while you make up the others.
Top with whatever you wish. Freeze any leftovers for another time.