Step 1

Grease and line two large baking sheets with baking parchment.

Step 2

Place the flour, cocoa powder, baking powder, bicarbonate of soda and salt in a medium mixing bowl. Stir everything together to combine.

Step 3

Cream the butter and both sugars together until well combined, about 2-3 minutes if usnig an electric mixer.

Step 4

In a separate small bowl, mix together the egg, vanilla extract, sour cream and red food colour paste until smooth. Add this red tinted mixture to the creamed butter and sugar and mix well, scraping down the sides of the bowl with a plastic scraper to make sure everything is thoroughly combined.

Step 5

Tip in the bowl of dry ingredients and mix until you have a soft cookie dough. Fold in 125g of the white chocolate chips or chunks. Place the cookie dough in the fridge for a minimum of one hour to firm up.

Step 6

When you're ready to bake, reheat the oven to 180C/160Fan/350F. Roll 25g (or 50g for jumbo cookies) sized balls of cookie dough in your hands (if you don't want red hands, wear disposable gloves!)

Step 7

Press the reserved white chocolate chunks or chips on top of the cookie dough balls. Place in the oven and bake for 10-12 minutes, or 14-16 minutes if you make jumbo cookies. They will still be quite soft in the middle, but will firm up on cooling. Leave on the baking tray for 5 minutes before transferring to a wire cooling rack.