Preheat the oven to 180°C/350°F (160°C fan) and line 2 baking trays with baking paper.
Place the butter cubes into the Thermomix bowl. Mix for 12 sec/speed 5 until softened. Scrape down the sides of the mixing bowl with a spatula.
Add both sugars. Mix for 20 sec/speed 4. Scrape down the bowl, then mix again for 15 sec/speed 4 until smooth and creamy.
Add the egg and vanilla extract. Mix for 15 sec/speed 3. Scrape down the bowl and mix again for 15 sec/speed 3.
Add the flour, bicarbonate of soda and salt. Mix for 10 sec/speed 4, scrape down the bowl, then mix again for 3 sec/speed 4.
Stir in the dried cranberries and white chocolate chips with a spatula. Tip:Transfer the dough to a regular mixing bowl. I find it much easier to scoop and shape the dough this way without the Thermomix blades getting in the way.
Roll the dough into walnut-sized balls and place them 5 cm apart on two baking trays. Press a few extra white chocolate chips and cranberries on top. Tip: If the dough feels too soft, chill it for 20 minutes before shaping.
Bake one tray at a time for 12-14 minutes, until golden at the edges but still soft in the centre. Keep the second tray chilled in the fridge while the first bakes.
Leave the cookies on the trays for 5 minutes, then transfer them to a wire rack. They will firm up as they cool.
Notes
Storage: Store the cookies in an airtight container for up to 5 days. Freeze for up to 2 months, then thaw at room temperature.