In a small bowl, sift together all the ingredients for the chai spice blend. Store in an airtight container for up to a year.
Cookies
Browning the butter is technically optional but the extra time is SO worth it! The biggest problem I see people run into when using brown butter in cookies, is not letting the butter cool completely to room temperature before adding it to the dough. So I highly recommend browning the butter the night before you want to make these chai cookies.
Using a stand or hand mixer, cream together the brown butter, brown sugar, and granulated sugar until smooth and creamy.
Add in the eggs and vanilla bean paste and beat until light, fluffy, and pale in color. This should take 2-4 minutes which seems like a long time, but you'll see a huge difference in the texture afterwards.
Stir in the flour, chai spice, baking soda, and salt and mix until thoroughly combined. The dough should be wet and sticky.
In a small bowl, whisk together the granulated sugar and chai spice for the topping.
Spoon a generous 3 tablespoons of dough and then roll cookie dough balls in chai sugar.
Cover the dough balls and chill in the fridge overnight (minimum of 2 hours if you just can't wait).
Preheat your oven to 350°F and line a light colored baking sheet with parchment paper.
Place dough balls at least 2-3 inches apart on the baking sheet (they will spread, I usually only do 6 cookies on a half sheet pan). Place the rest of the cookie dough balls back in the fridge while the first batch cooks.
Bake cookies for on the center rack of the oven for 9-11 minute or until the edges are set and the centers are still soft.
Remove from the oven and let rest on the baking sheet for 2-3 minutes, then transfer to a cooling rack.
Glaze
In a small bowl, whisk together the powdered sugar and vanilla bean paste. Then slowly drizzle in the milk until the glaze is a thick, pipeable consistency.
Transfer to a piping bag piping bag (or small plastic bag) and cut the tip off to make a small hole.
Once the chai cookies are cool, drizzle with the vanilla bean glaze if desired! (Use as much or as little glaze as you want!)
Notes
To make brown butter, melt unsalted butter over medium heat, stirring frequently. Watch closely for the butter to develop brown specs and a nutty aroma. Once you start seeing brown specs, let cook for just a few seconds longer (watch very carefully or it will burn). Remove from the heat and pour into a small bowl so that it doesn't continue to cook. Set aside and let cool for about 20 minutes in the fridge until soft and pliable. I recommend making the brown butter the night before you make the cookies, so that it has time to fully cool to room temperature! Note: For every ½ cup (1 stick or 113g), you'll lose about 1 tablespoon (14g) to evaporation while cooking. So you can either add in an extra 1 tablespoon before browning, or if you're browning big batches, just make up the weight difference in your recipe with regular unsalted butter if needed.Store cookies in an airtight container at room temperature for up to 4 days (they'll definitely be gone before then though).Freeze pre-rolled cookie dough balls in the freezer for up to 6 months.