Preheat the oven to 180C (160C fan, gas mark 4). Grease the bundt pan.
In a medium bowl, whisk together flour, baking powder and baking soda. Set aside.
In a separate large bowl, cream together butter and Tate & Lyle Pure Cane Granulated Sugar.
Add eggs, one at a time, mixing well with the hand mixer after each addition.
Mix in vanilla extract and sour cream until combined.
Gently add the flour in three batches using a silicone spatula.
Finally, stir in the milk until smooth.
For the Cinnamon Filling
To make the cinnamon filling, whisk together Tate & Lyle Dark Brown Soft Sugar and cinnamon,
Now assemble the cake in the bundt pan. Using a ice-cream scoop, scoop out about 1/3 of the batter into the bottom of the pan, even it out with the spatula, then sprinkle with half of the cinnamon filling. Cover the cinnamon filling with half of the remaining cake batter, slightly even out with the spatula and sprinkle with the second half of the cinnamon filling.
Finally, spread the remaining batter over the cinnamon filling. It's ok if the final layer of the batter is thinner and a bit messy. Just make sure it's more-less even and covers the whole amount of cinnamon.
Bake for 45-50 minutes or until a toothpick inserted into the centre comes out clean.
Allow to cool down completely before taking out of the pan (at least 2hours at room temperature).
For the Icing
To make the icing, whisk Tate & Lyle Cane Icing Sugar and milk until smooth. If the icing is too thick for your liking, add more milk (1/2 tsp at a time), and if it's too thin, add more icing sugar until desired consistency is reached.
Remove the cake from the pan, drizzle with icing and sprinkle with chopped walnuts.
Add a few tablespoons of cream cheese instead of milk to the icing if you want a bit of freshness.
This cake lasts long, just make sure to cover it with foil or put in the container and you can enjoy it for the whole week (if it survives that long).