Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, cocoa powder, instant espresso, baking soda, baking powder, salt and cinnamon.
In a small bowl or measuring cup, whisk together the sour cream, egg and pure vanilla extract. Set aside until needed.
In the bowl of a stand mixer, using the paddle attachment, cream the butter and Redpath® Dark Brown Sugar on medium-high speed until mixture is pale in colour and creamy; about 3 minutes.
Add in a third of the flour mixture. Mix until just moistened. Add in half of the sour cream mixture, mixing until just combined. Repeat process with the remaining dry and wet ingredients, ensuring to scrape down the bowl after each addition.
Using a small ice cream scoop (1 ¼ inch / 3 centimetre scoop), scoop equal sized mounds onto the lined baking sheet. Place baking sheet into the fridge to chill slightly; about 10 minutes. Shape chilled mounds into balls before placing into the preheated oven.
Bake for 10 to 15 minutes, or until a skewer inserted into the centre of a cookie comes out clean. Take out of the oven and let cool slightly on the pan for 5 minutes before carefully transferring to a wire cooling rack to cool completely.
For the cream cheese filling:
In the bowl of a stand mixer, fitted with paddle attachment, blend the cream cheese until smooth on medium speed. Scrape down sides of bowl, add softened butter, and beat until thoroughly combined and no lumps remain. Add in the sour cream, vanilla extract, and salt. Blend until fully incorporated. On low speed, sift in Redpath® Icing Sugar in four parts. After each addition, cream until smooth. Do not overmix. Fit a piping bag with a star or plain piping tip. Fill bag with the cream cheese filling. Set aside. If the filling is too soft, place into the fridge to slightly firm up before piping.
For the assembly:
Pipe about a tablespoon amount of the cream cheese filling onto the flat side (bottom) of one cookie. Gently press another cookie, flat side down, onto the filling. Repeat process with the remaining cookie halves until all whoopie pies are assembled.
Place finished cookies in the fridge to allow the filling to set; about 5 minutes. Mini Chocolate Whoopie Pies can be kept in an airtight container in the fridge for up to 4 days.