1. Cook raspberries over medium heat until soft, then strain through a sieve to remove seeds. You should get about 80g raspberry juice.

2. Mix juice with lemon juice and set aside.

3. Whisk sugar, egg, egg yolk, and salt in a heatproof bowl until slightly fluffy.

4. Heat the raspberry-lemon mixture until just boiling, then remove from heat.

5. Slowly drizzle the hot mixture into the egg mixture while whisking constantly to temper.

6. Return all to saucepan and cook over low heat, stirring constantly, until thick enough to coat a spoon (4–6 min). Do not boil.

7. Remove from heat. Stir in butter and vanilla until smooth.

8. Pour into container, press plastic wrap onto surface, and chill for at least 1 hour.

9. Mix sugar and lemon zest in a large bowl by rubbing with fingers to release oils.

10. Add melted butter, eggs, lemon juice, and vanilla. Whisk until combined.

11. In a separate bowl, combine flour, xanthan gum, baking powder, and salt.

12. Add dry ingredients to wet and mix into a soft, sticky dough.

13. Chill dough in fridge for at least 2 hours or overnight.

14. Preheat oven to 350ºF (180ºC). Line baking sheets with parchment.

15. Scoop dough using a 2-tbsp scoop, roll in powdered sugar, and form balls.

16. Place on baking sheet, spaced apart.

17. Press a ½-tbsp indent into each and fill with 1 tsp raspberry curd.

18. Bake for 9–12 minutes until edges are set and cookies are cracked.

19. Cool 5–10 min on sheet, then move to rack. Chill for best texture.