Pre-heat your oven to 180°C/160°C fan
Coat your bundt tin with homemade cake release or cake release spray. I use a 3 litre bundt tin, but the mixture doesn't fully fill the tin so you could use one a little smaller.
Beat together the margarine/butter (330g) and caster sugar (330g) until fully combined and light and fluffy.
Add the vanilla extract (½ tsp) and beat in the eggs (6 large) one at a time, ensuring each egg is fully combined before adding the next one. If your mixture starts to look a little split, then beat in 1 tbsp of your flour to the mixture.
Add the self-raising flour (360g) and fold into the other ingredients, taking care not to knock out all of the air beaten in previously.
Pour your cake batter into the prepared tin.
Bake for 45 minutes, until a skewer inserted into the centre of the cake comes out clean.
Leave the cake to cool into the tin for about 10 minutes before turning it out onto a wire rack to cool completely.