Preheat oven to 300 degrees F (150 degrees C) and grease pans. Line bottoms with rounds of parchment paper.
Finely chop Semi-Sweet Chocolate Chips (3 ounce) and in a bowl combine with Coffee (1 1/2 cup). Let mixture stand, stirring occasionally, until chocolate is melted and mixture is smooth.
Into a large bowl sift together Granulated Sugar (3 cup), All-Purpose Flour (2 1/2 cup), Unsweetened Cocoa Powder (1 1/2 cup), Baking Soda (2 teaspoon), Baking Powder (3/4 teaspoon), and Salt (1 1/4 teaspoon).
In another large bowl with an electric mixer beat Large Egg (3) until thickened slightly and lemon colored.
Slowly add Vegetable Oil (3/4 cup), Buttermilk (1 1/2 cup), Vanilla Extract (3/4 teaspoon), and melted chocolate mixture to eggs, beating until combined well. Add sugar mixture and beat on medium speed until just combined.
Divide batter between pans, being sure not to fill pans higher than 2/3 full.
Bake in middle of oven until a tester inserted in center comes out clean, about 1 hour and 10 minutes.
Meanwhile, make the icing: In a small saucepan over direct heat set on low, melt the Semi-Sweet Chocolate Chips (4 ounce). Stir in the Powdered Confectioners Sugar (1/4 cup). Stir in the Egg (3), whisking constantly.
Cook over low to medium-low until thick. Stir in the Butter (1/4 cup) one tablespoon at a time. Set aside to cool. Transfer to a glass measuring cup with a spout for easy pouring.
Cool layers completely in pans on racks, about 10 minutes.
Run a thin knife around edges of pans and invert layers onto racks. Remove parchment paper and cool layers completely. Cake layers may be made 1 day ahead and kept, wrapped well in plastic wrap, at room temperature.
If you are making a layer cake, spread icing over one cake layer. Top layer with other cake layer. Pour icing on top of top layer and with an off-set spatula spread it all over the sides. Cake keeps, covered and chilled, 3 days. Bring cake to room temperature before serving.