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 through 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 color.

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

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

Return the mixture to the saucepan and cook it over low heat with constant stirring until thickened.

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

Pour the finished raspberry curd into a bowl and cover with plastic wrap in direct contact with the surface to prevent skin formation.

Allow it to cool completely to room temperature, then chill it in the fridge for at least 1 hour or until thickened.

Add the sugar and lemon zest to a large bowl, and 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, then add them to the wet ingredients.

Mix until you get a smooth, batter-like cookie dough.

Chill the cookie dough in the fridge for at least 2 hours before proceeding to the next step.

Adjust the oven rack to the middle position, pre-heat the oven to 350ºF (180ºC) and line two large baking sheets with parchment paper.

Use a 2-tablespoon cookie scoop to scoop out a portion of the cookie dough, roll it in powdered sugar until evenly coated.

Place the sugar-coated cookie dough balls onto the lined baking sheets, with plenty of 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 (generous) teaspoon of raspberry curd.

Bake one baking sheet at a time at 350ºF (180ºC) for 9-12 minutes until cookies have spread and cracked around edges.

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

These cookies are best when chilled from the fridge.