Prepare the blackberry curd.
Zest and juice the limes, setting aside for later. (You will need 2 to 3 limes for all of the zest and juice needed for the recipe.)
Add the flour and powdered sugar to a small bowl, whisk and set aside.
Add the lime zest and sugar to a medium bowl. Rub the zest and sugar together until all of the sugar is coated in in zest.
Add the butter to the sugar mixture. Using a handheld mixer, cream the butter and sugar mixture at medium-high speed for 2 minutes.
Add the yogurt and lime juice and continue blending at medium-high speed for another minute.
Add the dry ingredients to the wet ingredients and blend at medium speed until no more flour can be seen.
Line a pan with parchment paper and begin scooping the dough balls. Each cookie is 1 tablespoon of dough. Scoop the dough, roll it between your palms to form it into a ball and place it on the prepared pan. Repeat with the rest of the batter.
Once all of the dough balls have been scooped and place on the prepared pan, indent each dough ball with ½ teaspoon measuring spoon.
Once all of the cookies have been indented, cover and place them in the refrigerator for one hour.
Once the cookies have chilled for 1 hour, preheat the oven to 350F. Remove the cookies from the refrigerator. Line a new (room temperature) pan with parchment paper and place the cookies on it. (If you can't bake all of the cookies at the same time, return any unbaked cookies to the refrigerator until you are ready to bake them.) Fill each indentation with blackberry curd. Each cookie only needs an even ½ teaspoon of curd, make sure not to over fill the cookies.
Bake the cookies for 13 minutes - the cookie and filling will be set. Let the cookies cool on the pan for about 5 minutes before transferring them to a cooling rack.