Preheat your oven to 180°C (350°F) for standard baking or 160°C (320°F) for fan-forced. Grease and line an 8-inch round cake pan with baking or parchment paper.

In a large mixing bowl, use an electric mixer to beat the room temperature butter, sugar, and vanilla extract together until the mixture becomes pale and creamy, about 1-2 minutes.

Add the eggs one at a time to the butter mixture, mixing briefly after each addition. Scrape down the sides of the bowl to ensure all ingredients are well combined.

In a separate bowl, whisk together the plain flour, baking powder, ground cinnamon, and salt.

Pour half of this flour mixture into the butter mixture, followed by all the milk. Mix slowly on low speed until combined.

Add the remaining flour mixture and continue mixing until the batter is smooth and creamy.

Pour the batter into your prepared cake tin and bake it in the oven for approximately 30-35 minutes, or until a skewer inserted into the middle comes out clean.

Once the cake is still warm, generously brush the top with melted butter and sprinkle over the mixture of ground cinnamon and sugar.