Classic Chocolate Layer Cake

Today is my birthday! For this birthday, Jay and Aishwarya asked me what sort of cake I would like them to make for me; and I wanted something loaded with chocolate. I had seen this recipe at Annie's Eats sometime back and had bookmarked it. So all it needed from me was to direct them to this. They made this chocolate wonder and which surely made my special day even more special.
Recipe source: Annies eats
Ingredients:
1¼ cups (6¼ oz.) all-purpose flour
1 cup (3 oz.) unsweetened cocoa powder, plus more for dusting the pans
2 tsp. instant espresso or coffee powder
1 cup boiling water
½ cup sour cream
2 tsp. vanilla extract
1 cup (2 sticks) unsalted butter, at room temperature
1¾ cups (12¼ oz.) sugar
2 large eggs, at room temperature
1 tsp. baking soda
½ tsp. salt
For the frosting:
9.5 oz. bittersweet chocolate, finely chopped
6 oz. cream cheese, at room temperature
6 tbsp. unsalted butter, at room temperature
2 cups confectioners’ sugar, sifted
4 tbsp. unsweetened Dutch-process cocoa powder
Pinch of salt
2/3 cup plus 1 tbsp. sour cream
Method:
To make the cake, preheat the oven to 350˚ F.  Butter two 8-inch x 2-inch round cake pans. Line with parchment paper, then butter and flour the pans.  In a medium bowl, combine the cocoa powder, espresso powder, and boiling water.  Whisk until smooth; set aside to cool slightly.  When cooled down a bit, whisk in the sour cream and vanilla.  Set aside.  In the bowl of an electric mixer, beat the butter on medium-high speed until smooth, about 1 minute.  Gradually blend in the sugar and whip on medium-high speed until light and fluffy, 2-3 minutes more.  Blend in the eggs one at a time.  In a medium bowl, combine the flour, baking soda, and salt; whisk to blend.

With the mixer on low speed, add the dry ingredients in three additions alternating with the sour cream mixture, beating each addition just until incorporated.  Divide the batter evenly between the prepared pans.  Bake the cake layers for about 23-27 minutes or until a toothpick inserted in the center comes out clean, rotating the pans during halfway through to ensure even baking.  Transfer the baked cake layers to a wire rack and let cool in the pans at least 30 minutes before inverting onto the rack to cool completely.

To make the frosting, melt the chocolate in a heat-proof bowl set over a pot of simmering water or microwave the chocolate for 30 seconds give a stir and microwave for another 30 seconds.Stir and now microwave at 10 second intervals till the chocolate melts.  Set aside to cool until just barely warm.  In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese and butter on medium-high speed until pale and fluffy, about 3-4 minutes.  Gradually mix in the confectioners’ sugar, cocoa powder and salt.  Beat in the melted and cooled chocolate and then the sour cream.  Continue beating until the mixture is smooth and well blended.

To assemble the cake, place one of the cake layers on a cake board or serving platter.  Spread an even layer of the frosting over the top of the cake.  Top with the second cake layer.  Frost the top and sides of the cake again using an offset spatula or spoon for a soft, billowy appearance.  Slice and serve.