Preheat the oven to 350°. line 2 baking sheets with parchment paper. Spread the sesame seeds on a plate. Mix the dry ingredients together: whisk flour, baking powder, and salt in a medium bowl. Using an electric mixer on medium speed, beat butter, sugar, and honey in a large bowl until light and fluffy, about 3 minutes. Beat in tahini, then gradually add dry ingredients, until all combined. Dough will be slightly sticky.

Scoop out heaping tablespoons of dough (about 1 oz.) and roll into balls. Roll it in the sesame seeds and flatten it on the parchment-lined baking sheets, spacing about 2″ apart. Bake cookies, rotating baking sheets halfway through, until golden brown, 13–15 minutes. Let cool on baking sheets (cookies will firm as they cool).
Meanwhile, make the glaze: Whisk the remaining 1 cup confectioners’ sugar, vanilla, water and 2 pinches of salt in a medium bowl. Dip the top of each cookie in the glaze to cover evenly; let any excess drip off.