Piped Chocolate Butter Cookies

You need just 9 basic ingredients and a large piping tip to make these meltinyourmouth chocolate butter cookies. Theres no leavening so the texture is similar to shortbread cookies. Review recipe Notes before beginning and I strongly recommend chilling the piped cookies for at least 2030 minutes before baking.
Ingredients
1 cup 16 Tbsp 226g unsalted butter softened to room temperature
34 cup 150g granulated sugar
1 large egg at room temperature
1 and 12 teaspoons pure vanilla extract
2 cups 250g allpurpose flour spooned leveled
13 cup 27g natural or dutchprocess unsweetened cocoa powder
14 teaspoon salt
2 Tablespoons 30ml milk warm
1 teaspoon espresso powder
Optional Toppings
4 ounces 113g semisweet chocolate finely chopped
maraschino cherries
sprinkles or coarse sugar
Instructions
Read through the recipe and recipe Notes before beginning. Make room in your refrigerator for a baking sheet so the shaped cookies can chill for 2030 minutes. Without chilling the piped cookies will overspread. If you chill the dough prior to shaping the dough will be too coldstiff to pipe.
Line 23 large baking sheets with parchment paper or silicone baking mats or leave unlined. If unlined do not grease the pan.
In a large bowl using a handheld mixer or a stand mixer fitted with a paddle attachment beat the butter on mediumhigh speed until very soft and creamy about 2 minutes. Add granulated sugar to the butter and beat together on mediumhigh speed until smooth and creamed another 2 minutes. Add the egg and vanilla and beat on high speed until combined about 1 minute. Scrape down the sides and up the bottom of the bowl and beat again as needed to combine
On low speed beat in the flour cocoa powder and salt. Turn up to high speed and beat until completely combined.
Warm the milk to about 150F 66Cabout 20 seconds in the microwavethen mix in the espresso powder until it dissolves. Add the warm espressomilk mixture to the dough and beat on medium speed. You want a dough thats creamy and pipeable but still thick so you may need another 12 Tablespoon of milk. Tip The more milk you add the more the cookies will spread so chilling in step 7 is imperative. I