Add the raspberries to a small saucepan and cook them over medium heat until they've completely softened and released their juices.

Pass the softened raspberries though a sieve, placed over a small bowl or jug, to remove the seeds and other solids.

Return the raspberry juices to the saucepan and add the lemon juice. Set aside until needed.

In a heat-proof bowl, whisk together the sugar, egg, egg yolk and salt until slightly fluffy and paler in colour.

Cook the raspberry-lemon juice mixture over medium heat until it only just comes to a boil. Remove from heat immediately.

Add the hot raspberry juices to the egg-sugar mixture in a slow drizzle, whisking constantly.

Return the mixture to the saucepan and cook over low heat with constant stirring until thickened (4-6 minutes).

Once thickened, remove from heat and stir in the butter until melted. Add the vanilla and mix well.

Pour the finished raspberry curd into a bowl and cover with plastic wrap touching the surface. Chill in the fridge for at least 1 hour.

Add the sugar and lemon zest to a large bowl, rub the zest into the sugar.

Add the melted butter, eggs, lemon juice and vanilla, and whisk well until combined.

In a separate bowl, whisk together the gluten free flour blend, xanthan gum, baking powder and salt, and add them to the wet ingredients.

Mix until you get a smooth, batter-like cookie dough. Chill in the fridge for at least 2 hours.

Preheat the oven to 350ºF (180ºC) and line two large baking sheets with parchment paper.

Scoop out portions of the cookie dough, roll in powdered sugar to coat.

Place the sugar-coated cookie dough balls onto the lined baking sheets, with space between them.

Use a ½-tablespoon measuring spoon to make an indent in the center of each cookie dough ball.

Fill the cookies with about 1 teaspoon of raspberry curd.

Bake for 9-12 minutes until the cookies have spread and cracked around the edges.

Allow cookies to cool on the baking sheet for about 5-10 minutes before transferring to a wire rack.