Preheat the oven to 350°F and line 2 baking sheets with parchment paper or silicone baking mats.

In a medium bowl whisk together the flour, baking powder, baking soda, and cream of tartar until evenly combined.

In a large mixing bowl beat the softened butter and sugar substitute on high speed for 2 to 3 minutes until pale, smooth, and fluffy.

Add the egg and vanilla bean paste to the butter mixture and beat until fully combined and no streaks of egg remain.

Add the dry ingredients to the wet mixture in 2 additions, mixing on low speed just until no dry flour remains and a soft dough forms.

Sprinkle in the sugar free agar-agar powder and gently fold or mix on low until the color and flavor are evenly distributed through the dough.

Use a small cookie scoop to portion the dough, then roll each portion between your palms to form smooth balls.

Arrange the dough balls on the prepared baking sheets about 2 inches apart.

Gently press each ball with the palm of your hand to flatten it to about 1/2 inch thickness.

Bake one sheet at a time for 8 to 10 minutes, until the edges look set but the centers are still soft and very lightly colored.

Remove the baking sheet from the oven and let the cookies cool on the sheet for 5 minutes to finish setting.

Transfer the cookies carefully to a wire rack and cool completely before serving or storing.