How to make Shortbread Cookie like Walkers Style. Here's what you'll need: 1 cup salted butter (227g) room temp 1 cup powdered sugar (100g) 1/2 tbsp vanilla extract (7ml) 1 cup powdered milk (100g) trust me this makes the shortbread cookie rich and buttery 2 cups all purpose flour (250g) 1. Preheat oven at 160℃ or 325℉. 2. Mix together butter and icing until smooth. 3. Add vanilla and mix. 4. Add powdered milk then mix. 5. Add flour in two batches. Mixing after every addition. 6. Continue mixing