Prepare the Dry Ingredients: In a medium bowl, whisk together the plain flour, baking powder, and salt. Set this aside for later.

Cream the Butter and Sugar: In a large bowl using a stand mixer with the paddle attachment or a hand mixer, beat the softened butter and caster sugar on medium-high speed for 3-4 minutes, until the mixture is light, pale, and fluffy. Scrape down the sides of the bowl as needed.

Add Wet Ingredients: Add the egg and vanilla extract to the butter mixture and beat on medium speed until fully combined, about 1 minute. The mixture should be smooth.

Combine Wet and Dry: Reduce the mixer speed to low and gradually add the flour mixture. Mix until just combined – be careful not to overmix, as this can make the cookies tough. The dough will be soft.

Roll and Fill the Dough: Tip the dough out onto a large sheet of parchment paper. Place another sheet on top and roll the dough into a rectangle approximately 30cm by 25cm. Remove the top sheet. In a small bowl, mix the melted butter, dark brown sugar, and cinnamon until it forms a paste. Spread this filling evenly over the dough, leaving a small 1cm border along one of the long edges.

Create the Log and Chill: Starting from the long edge opposite the clean border, tightly roll the dough into a log, using the parchment paper to help you. Wrap the log securely in the parchment or cling film. Place it in the freezer for at least 1 hour (or in the fridge for 2-3 hours) until very firm. I find the freezer works best for a cleaner cut.

Preheat and Slice: Preheat your oven to 180°C (160°C fan). Line two large baking trays with parchment paper. Once the log is firm, use a sharp knife to slice it into 1cm thick rounds. You should get about 24 cookies.

Bake the Cookies: Place the cookie slices on the prepared baking trays, leaving about 5cm of space between them as they will spread. Bake for 12-15 minutes, or until the edges are lightly golden brown. The centres should still look a little soft.

Cool and Ice: Let the cookies cool on the baking trays for 5 minutes before transferring them to a wire rack to cool completely. While they cool, make the icing. In a small bowl, beat the softened cream cheese, sifted icing sugar, and vanilla extract until smooth. Add milk, 1 tablespoon at a time, until you reach your desired drizzling consistency. Drizzle the icing over the cooled cookies.