-
1
Preheat the oven to 350u00b0 F. Grease an 8 x 8-inch square cake pan.
-
2
Using an electric mixer, beat the butter in a large bowl until smooth. Add the sugar and eggs; beat until lightened in color. Add the cocoa, baking soda, vanilla extract, and salt, then mix well. Beat in the flour in 3 additions, alternating with the sour cream (begin and end with the flour). Add the hot coffee and mix until a smooth batter forms.
-
3
Pour the batter into the prepared pan. Bake until a toothpick tester comes out clean, approximately 40 to 50 minutes. Cool the cake in the pan for 10 minutes before inverting and cooling completely on a wire rack. Wrap the cake in plastic wrap and transfer it to the freezer until it is partially frozen, about 1 hour.
-
4
Level the top with a serrated knife (if needed) and cut it into 12 even fingers.
-
5
For the cream filling, whisk together the milk and flour in a small saucepan. Heat over medium-high heat, stirring constantly until the mixture thickens to a pudding-like consistency. Remove the pan from the heat source and transfer the mixture to a shallow dish, and refrigerate until completely cool.
-
6
In a mixing bowl, cream 1/2 cup softened butter and granulated sugar until well-combined. Add the cooled milk mixture and whip on high speed until fluffy, about 5 minutes. Add 1/2 cup confectioners' sugar and 1/2 teaspoon vanilla extract, beat until well-combined. Transfer to a piping bag or a zip-top bag with the corner snipped. Cut a slit lengthwise on top of each snack cake and pipe in a little of the cream in the centers.
-
7
For the frosting, place the cocoa powder, the remaining confectioners' sugar, and butter in a large mixing bowl. Beat until just incorporated. Add the chocolate syrup, 1/2 teaspoon vanilla extract, and salt. Beat until well-combined. Transfer the frosting to a piping bag fitted with a large Cake Icer Decorator Tip (#789) and pipe the frosting on top of each cake. Alternatively, you may spread the icing on top of the cakes with a spatula, then drag the tines of a fork through it to create an authentic appearance.
-
8
Store the cakes in an air-tight container for up to two days (if they last that long!).
