Prepare Dry Ingredients: In a medium bowl, whisk together the plain flour, bicarbonate of soda, and salt. Set this aside for later. This step ensures the raising agent and salt are evenly distributed.

Cream Butter and Sugars: In a large bowl using a stand mixer or an electric hand mixer, beat the softened unsalted butter with the granulated sugar and light brown sugar on medium-high speed for about 3-4 minutes. You’re looking for a light, pale, and fluffy texture. This process of creaming butter and sugar incorporates air, which is essential for a tender cookie.

Add Wet Ingredients: Add the egg and vanilla extract to the butter mixture and beat again until everything is well combined. Scrape down the sides of the bowl to ensure no bits are left behind.

Combine Dough: Gradually add the dry flour mixture to the wet ingredients in two or three additions, mixing on a low speed until just combined. Be careful not to overmix at this stage; stop as soon as you no longer see streaks of flour.

Make the Cheesecake Filling: In a separate small bowl, beat the softened cream cheese, sifted icing sugar, vanilla extract, and pinch of salt with a hand mixer or a sturdy whisk until it's completely smooth and creamy.

Assemble the Cookies: Line two baking trays with parchment paper. Scoop out tablespoon-sized portions of cookie dough (about 30g each) and roll them into smooth balls. Arrange them on the prepared trays, leaving some space between each one. Using your thumb or the back of a rounded teaspoon, gently press an indentation into the centre of each dough ball.

Fill and Chill: Spoon about half a teaspoon of the cheesecake filling into each indentation. Then, top the cheesecake filling with a small dot of strawberry jam. Place the entire baking tray in the refrigerator to chill for at least 30 minutes. I find this step is absolutely non-negotiable for texture and shape.

Bake to Perfection: While the cookies are chilling, preheat your oven to 180°C (160°C fan). Once chilled, bake the cookies for 12-14 minutes, or until the edges are lightly golden brown. The centres should still look soft and slightly underdone when you take them out.

Cool Completely: Let the cookies cool on the baking tray for 5-10 minutes before carefully transferring them to a wire rack to cool completely. They will firm up as they cool.