Cook raspberries in a saucepan over medium heat until soft.

Strain raspberries to remove seeds, yielding about ⅓ cup of juice.

Combine raspberry juice with lemon juice in the saucepan.

Whisk sugar, egg, egg yolk, and salt in a heatproof bowl.

Heat the raspberry-lemon juice until it just boils, then slowly whisk it into the egg mixture.

Return to the saucepan and cook on low heat, stirring constantly until thickened.

Remove from heat, stir in butter until melted, then add vanilla.

Pour curd into a bowl, cover with plastic wrap touching the surface, and chill for at least 1 hour.

Rub the sugar and lemon zest together in a large bowl.

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

Whisk gluten-free flour, xanthan gum, baking powder, and salt in another bowl, then add to wet ingredients and mix until smooth.

Chill dough in the fridge for at least 2 hours.

Preheat oven to 350°F (180°C) and line baking sheets with parchment paper.

Scoop 2 tbsp portions of dough, roll in powdered sugar and shape into balls.

Place dough balls on baking sheets, make an indent in each and fill with 1 teaspoon of raspberry curd.

Bake one sheet at a time for 9-12 minutes, until the edges are crispy.

Let cookies cool on the baking sheet for 5-10 minutes, then transfer to a wire rack to cool completely.

Storage: Store cookies in an airtight container at room temperature for 2-3 days or in the fridge for up to a week. Extra raspberry curd can be stored in the fridge for up to 10 days.