Preheat the oven to 180c.
Line 2 baking sheets with parchment paper and set aside.
In a large mixing bowl, combine butter, granulated sugar and brown sugar and beat with an electric mixer until light and fluffy.
170 g salted butter, 150 g granulated white sugar, 100 g light brown sugar
Add the egg and vanilla and briefly mix to combine.
1 egg, 1½ teaspoon vanilla extract
Fold in blueberries, white chocolate chips and lemon zest.
100 g dried blueberries, zest of 2 lemons, 90 g white chocolate chips
Add plain flour, corn flour, bicarbonate of soda, cream of tartar, salt and cinnamon and mix until just incorporated.
270 g plain (all-purpose) flour, 1 tablespoon corn flour, ¾ teaspoon bicarbonate of soda (bicarb soda/baking soda), ½ teaspoon cream of tartar, pinch of cinnamon, ¼ teaspoon fine (cooking) salt
To shape the cookies, using your hands roll a scant ¼ cup of the dough into a ball (doesn't need to be perfect), then pinch the ball roughly in half.
Place one-half of the ball onto the prepared baking sheet, then roll the other half into a ball and place it on top, pressing down slightly to stabilise it. Repeat for the remaining dough.
Bake for 8-10 minutes, or until the cookies are lightly browned on the edges but the centre is still underbaked (you may need to rotate the baking sheets during the cooking time depending on your oven).
As soon as the cookies come out of the oven, place a large drinking glass (see my notes for alternatives) upside over the top of a cookie and swirl it in a circle to push in the edges.
Allow the cookies to cool on the baking sheet for 5-10 minutes, before carefully transferring them to a wire cooling rack to cool completely.