Preheat the oven to 180°C / fan 160°C / gas 4. Line two baking sheets with greaseproof paper. Sift the flour and salt into a bowl. Stir in the butter, sugars, egg yolks, vanilla extract and food colouring to form a soft dough.
Divide into 20-25 balls and place them on the baking sheets, spacing them well. Press the Maltesers Teasers chunks into the biscuits and flatten them slightly. Bake for 10-14 minutes.
Remove from the heat and leave on the trays for a few minutes before transferring to a wire rack. Cool completely before tucking in.