In a large bowl, mix together the melted butter, caster sugar and brown sugar. Then stir in the egg, the vanilla extract and the black food colouring.
Mix the flour in with your spoon then mix well to make a thick, sticky dough.
Pour the milk chocolate chips into the bowl and gently stir them in.
Divide the dough into 12 equal pieces and roll each piece into a ball.
Place the balls onto a lined tray and freeze for 1 hour.
Preheat your oven to 180°C/350℉ (or 160°C/320°F for fan and convection ovens).
Spread the balls 2-3 inches apart on the tray to allow space for spreading. I usually bake 4-5 per tray at a time.
Bake for 14-15 minutes, until firm to the touch around the edges. The centres may look underbaked at first but they will continue to firm up as they cool down.
While the cookies are still hot fresh out of the oven, gently press Orange Smarties and extra chocolate chips on top.
Leave the cookies on the tray until completely cool then enjoy!