01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk flour, salt, and all chai spices in a medium bowl until evenly distributed.
03 - Beat butter and powdered sugar in a large bowl until light and fluffy. Incorporate vanilla extract.
04 - Gradually add flour mixture to butter mixture, mixing until just combined. Avoid overworking.
05 - Roll dough on lightly floured surface to 1/4-inch thickness. Cut with 2-inch round cutter. Place cookies 1 inch apart on prepared sheets.
06 - Bake 12-15 minutes until edges are just golden. Cool completely on wire rack.
07 - Beat butter until creamy. Gradually add powdered sugar, beating until fluffy. Mix in vanilla and chai spices. Add milk 1 teaspoon at a time until thick but spreadable.
08 - Spread or pipe 1-2 teaspoons filling onto bottom of one cookie. Top with another cookie. Repeat until all sandwiches are assembled.