Pre-heat your oven to 200C Fan/220C/400F/Gas Mark 6, and line a baking tray with baking paper
Mix the self raising flour and baking powder together a mixing bowl. Add the butter and rub it into the flour with your fingers or a fork ,until it resembles breadcrumbs
Add most of the cheddar to the flour and stir in (reserve 15-20g for topping the scones)
In another bowl whisk together the egg, milk and marmite
Reserve ½ tbsp of the marmite mixture for glazing the scones
Pour the rest of the marmite mixture into the flour and form a dough. If it's too dry, you can add an extra splash of milk
Pat it out onto a clean work surface (or a silicone mat) dusted with flour to about 2cm thick and cut out the scones using a round cutter, size of your choice (I used a 2.5" one). Push the cutter straight down and do not twist it
You will need to re-pat out the dough to use it all up
Glaze the scones with the reserved marmite mix, and sprinkle the reserved cheddar cheese on them
Bake for 10-12 minutes or until golden brown and risen. Remove from the oven and allow to cool, you can eat them warm or cold
Store in an airtight container and eat within 2 days. They can also be frozen