Heat oven to 325 degrees. Butter a 10-inch springform pan. Dust with 2 tablespoons cocoa powder.
In a medium saucepan over low heat, warm coffee, Irish whiskey, 12 tablespoons butter and remaining cocoa powder, whisking occasionally, until butter is melted. Whisk in sugars until dissolved. Remove from heat and cool completely.
In a bowl, whisk together flour, baking soda, salt, pepper and cloves. In another bowl, whisk together eggs and vanilla. Slowly whisk egg mixture into chocolate mixture. Add dry ingredients and whisk to combine. Fold in chocolate chips.
Pour batter into prepared pan. Transfer to oven and bake until a toothpick inserted in the center emerges clean, 55 to 65 minutes. Let cool on a wire rack, then remove sides of pan. Dust with powdered sugar before serving.