Preheat oven to 325°F (170°C). Spray 2 (8-inch) round cake pans with baking spray with flour.

In a medium saucepan, melt butter over medium heat. Whisk in cocoa; cook until fragrant, about 1 minute. Remove from heat; whisk in brown sugar, hot coffee, and buttermilk until sugar dissolves. Whisk in eggs and vanilla.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Gradually add flour mixture to cocoa mixture, whisking just until combined. Divide batter between prepared pans (about 3 cups or 685 grams each).

Bake until a wooden pick inserted in center comes out with a few moist crumbs, 40 to 45 minutes. Let cool in pans for 10 minutes. Invert cake layers onto a wire rack, and let cool completely.

Place 1 cooled cake layer on desired serving platter.

Unwrap cold Pistachio Kataifi Filling, and place on cake layer. Top with remaining cake layer. Spread Chocolate Buttercream on top and sides of cake. Pour Chocolate Ganache onto cake, using an offset spatula to push over edges. Garnish with reserved praline, if desired. Cover and refrigerate for up to 3 days.