2) In a large bowl, whisk flour, sugar, cocoa powder, bicarbonate of soda, baking powder and salt. Add oil, coffee and eggs. Beat at medium speed with an electric mixer until smooth. Mix in the sour cream and vanilla.
3) Spoon the batter evenly into prepared muffin cups, filling each two-thirds full. Bake until a tester inserted in centre comes out clean, 16-18 minutes. Let them cool in pans on wire racks for 5 minutes. Remove from the pans and cool completely on wire racks.
4) Spoon coffee cream filling into a squeeze bottle with a long narrow tip. Insert the tip into the top of cupcake and squeeze about 1 tablespoon of filling into centre of each cupcake.
5) Spread the coffee buttercream icing evenly over the cupcakes and garnish with chocolate-covered coffee beans, if desired.
Coffee cream filling:
In a small bowl, whip the cream cheese at medium speed with an electric mixer until smooth. Slowly add the liqueur and fold in the whipped topping. Cover and chill.
Coffee buttercream icing:
In a medium bowl, beat the butter at medium speed with an electric mixer until creamy. Gradually add the icing sugar, beating until smooth, then beat in the coffee.