In a large bowl, using an electric/stand mixer (or hand whisk, just double/triple the times) combine the butter and both sugars on medium speed for several minutes, until fully combined. Add the egg and vanilla and mix again.
In a small bowl, combine the spices to make the chai blend.
Add the flour, baking powder and 2 tsp of the chai spice blend and fold until combined. The dough should be fairly solid at this stage (it ought to almost form a ball, albeit a very soft one!). Place in fridge to chill for 30 minutes.
Place cookies 2 inches apart on baking sheets - they spread! Bake 12-14 minutes, until just golden at the edges. Let cool.