1. Line 2 baking sheets with baking parchment. Pour the melted butter into the bowl of a free standing mixer. Add the sugar, vanilla extract and vanilla ice cream and beat together, until well combined.
2. Gradually add the flour in four batches, mixing well after each addition, until you have a sticky cookie dough.
3. Carefully fold in the white chocolate chips and both types of sprinkles until evenly distributed. Place the dough in the fridge to chill for at least 1 hr or overnight.
4. Heat the oven to 180C/fan, 160C/gas 4. Divide the dough into 16 pieces and roll into balls. Place on the prepared trays, evenly spaced apart.
5. Bake for about 10 mins until golden brown around the edges.
6. Remove from the oven and leave on the baking sheets for 2 mins to firm up, then carefully transfer to a wire rack to cool completely.