Combine the butter and sugar in a stand mixer on medium speed or in a large bowl with a hand mixer and mix until pale and fluffy, about 5 minutes. Add the the tahini and vanilla extract and mix until well incorporated. Scrape down the bowl, the mix again to ensure tahini is combined.

In a medium sized separate bowl, whisk together the flour, baking powder, and salt. Add the dry ingredients to the tahini mixture and beat until just combined. Using an ice cream scoop, scoop the dough onto a plate lined with parchment paper in heaping tablespoon size rounds. Cover the plate with plastic wrap and refrigerate for at least 1 hour or overnight. [Option to freeze the cookie dough balls for up to 3 months]

Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper, and place the cookies on the prepared pans. They don't spread much, so feel free to place them close together. Bake for about 15 minutes, or until the edges are light brown, and the center is set. Allow to cool on the cookie sheet for 10 minutes, then transfer them to a wire rack to finish cooling. Store in an airtight container for up to 1 week, although I can guarantee they will not last long :)