Preheat the oven to 180 degrees℃ / 350℉.
Sift the self-raising flour (450 g) into a large bowl.
450 g self-raising flour
Cube the butter straight from the fridge.
110 g butter
Rub it into the flour until it resembles coarse breadcrumbs.
Stir in the caster sugar.
60 g caster sugar (superfine sugar)
Pour in the milk and stir with a spoon until it comes together as a dough.
300 ml milk
Transfer the dough to a floured work surface and bring it together in a ball so you can roll it out.
Roll the dough into a large rectangle using a rolling pin.
Mix the granulated sugar and cinnamon for the filling in a small bowl.
4 tbsp granulated sugar, 2.5 tsp ground cinnamon
Sprinkle it all over the dough, spreading it equally around so it covers it evenly.
From the long side of the rectangle, roll up the dough carefully and tightly into a large roll, as if you are making a Swiss roll.
Cut the roll into 12 equal pieces.
Grease your baking tin with a little oil, ensuring you cover all sides and edges, to prevent sticking.
Arrange the swirls in 4 rows of 3, leaving a little room between each roll as they will rise as they bake.
Bake for 25 minutes or until light golden in colour and cooked through.
Remove the baking tin from the oven and allow to cool.
In a separate small bowl, mix the icing sugar with the 2 tablespoons of milk to make a smooth, not too runny icing.
85 g icing sugar, 2 tbsp milk
Drizzle the icing over the cinnamon swirls and serve!