1) Start with separating egg whites and egg yolks. 

2) In a stand mixer, or using a hand mixer/hand whisk; whisk the egg whites until stiff peaks form. Set aside.

3) In a separate bowl, again using a stand mixer/hand mixer/hand whisk; whisk the egg yolks with sugar until pale, thick and foamy. 

4) Add oil and whisk for another minute, then add melted chocolate and sour cream and mix well. 

5) Mix together the sifted flour, baking powder and ground coffee. Add the dry ingredients to the egg yolk mixture and gently fold them in. 

6) Lastly, gently fold in the stiff egg whites. 

7) Grease and flour a 30 x 40cm baking sheet. Pour the cake batter in and spread it evenly all the way to the sides and corners of your tin. Bake in a preheated oven at 190C/170C fan for about 25 minutes. 

8) Let the cake cool down before handling it further. 

9) Whilst the cake is cooling down, prepare your filling. Whip the cream with some sugar and ground coffee. Set aside. 

10) Using a glass, cut out 12 uniform circles from your cake. Then, using a knife, gently cut each circle in half so that you’re left with two identical circles. You should have 24 identical circles in the end. 

11) Put the filling into a piping bag fitted with a decorating nozzle of your choice. 

12) Take one cake circle and pipe some cream on it. Then take another cake circle, place it on top and lightly press. 

13) Decorate the top of each of the coffee cakes with some melted white chocolate and whole coffee beans. Enjoy!