Bring the butter to room temperature. With an electric beater or stand mixer, beat the butter and salt for 1-2 minutes until it's the texture of thick mayonnaise. Add the sugar and beat for another 1-2 minutes until light and fluffy.
With the mixer on low, add the eggs one at a time and the vanilla. Scrape down the bowl to incorporate the eggs.
For the dry ingredients
Sift the flour and baking powder together. Keep the mixer on low speed and slowing add in the dry ingredients in stages until incorporated. Scrape down the bowl periodically. STOP MIXING as soon as the ingredients are incorporated!
Options for Chilling the Dough
Press the dough into one long log or two shorter logs and cover with parchment paper or plastic wrap. Chill in the fridge for at least two hours, or up to overnight.
If you are short on time, you can also freeze the logs for one hour until they are chilled.
For the Chai Spice Sugar Mixture
While the dough is chilling, grind the cardamom if using whole pods. Remove the seed from the shell and mix with the other spices. Grind together in a mortar and pestle or in a Ziploc bag with a rolling pin or the back of a small pan. It's ok if the seeds aren't completely ground.
You can certainly use pre-ground cardamom instead. Mix the remaining 5 Tbsp. sugar with the spices on a plate or bowl and set aside.
Unwrap the chilled dough and cut into 1-inch slices. Roll into balls and roll into the sugar and spice mixture to coat.
Preheat the oven to 400 degrees.
Place on a parchment-lined baking sheet 3 inches apart.
Bake for 8-10 minutes until they just start to crack on the surface. DON'T OVERBAKE! Remove from the oven and let cool on a rack before serving. If you are unsure if they are set in the middle, open up one cookie after they have cooled a bit. If they are still gooey, put back in the oven for 1 minute at a time. SET A TIMER!!
The cookie dough can be kept frozen for up to one month.