Whisk together the cake flour, cocoa powder, baking powder, salt, cinnamon, and espresso powder. Set aside.
In the bowl of a stand mixer, beat butter and sugars for 10 minutes until light and fluffy, scraping down the sides of the bowl occasionally. Then add egg, beating to incorporate. Stir in vanilla and milk, mixing thoroughly.
Beat flour mixture into the butter and egg mixture. By hand, gently stir in POM Pomegranate Arils. Cover dough with plastic wrap and chill for one hour.
Heat oven to 350°F. Line cookie sheets with parchment. Remove dough from refrigerator. Scoop 1 heaping teaspoon of dough per cookie, rolling each into a ball. Place 2 inches apart on a cookie sheet and bake until just done, 8 to 10 minutes, rotating pan halfway through.
¾ cup POM Pomegranate Arils
1¼ cups cake flour
1/3 cup unsweetened Dutch-processed cocoa powder
½ teaspoon baking powder
1 teaspoon salt
½ teaspoon ground cinnamon
½ teaspoon instant espresso powder
½ cup (1 stick) unsalted butter at room temperature