Chocolate Chai Spice Cookies

Cookie Dough
15 Preheat oven to 350℉ (180℃) and line a baking sheet with parchment paper.
2 Hand whisk together the flour, cocoa powder, baking powder, baking soda, espresso powder, spices, and salt in a medium bowl. Set aside. 
3 Place softened butter, brown sugar and granulated sugar in the bowl of a stand mixer with paddle attachment or large bowl with handheld mixer. Cream together on medium high speed until lighter in color and fluffy. About 3-4 minutes. Scrape the bottom and sides of the bowl halfway through mixing. 
5 On medium speed, mix in the egg followed by the egg yolk and vanilla until well blended. 
6 Mix in half the dry mixture at a time to firm a thick cookie dough.
Shape & Bake
17 Stir the chai sugar ingredients together in a medium shallow bowl.
10 Using a medium cookie scoop or spoon measure out the cookie dough into 35 grams balls. Take a 5 gram tablet of dark chocolate and press into the center of each cookie dough ball. Carefully shape the cookie dough around the chocolate to form a ball with the chocolate completely sealed in the middle. 
12 Roll each cookie ball in the chai sugar to coat.
18 Arrange the cookie balls on the prepared baking sheet, spacing about 2 inches apart. I bake 5-6 cookies at a time. 
13 Bake on the middle oven rack for 11-12 minutes. The centers will look puffed and there will be cracks around the edges.
19 Place the pan on a wire rack, leaving the cookies on the pan for 10 minutes before transferring directly onto a wire rack to cool. 
20 Enjoy cookies warm while the center chocolate is still melted. The chocolate center will firm as it cools, just like in chocolate chip cookies. Warm a cookie for 6-8 seconds in the microwave to re-melt the centers if you like before eating.