Step 1

Preheat oven to 160C.

Step 2

Grease a 28 x 18 cm baking tin and line bottom with baking paper, overlapping paper at opposite long ends for ease of removal.

Step 3

Beat the butter and sugar in a small bowl until creamy.

Step 4

Add the eggs one at a time, beating well after each addition.

Step 5

Mix the vanilla and coffee in 1 tablespoon warm water, stir until dissolved.

Step 6

Add coffee to butter mixture and beat until combined.

Step 7

Pour mixture into a large bowl.

Step 8

With a large spoon fold in the sifted flours alternately with the sour cream. Stir until just combined.

Step 9

Spoon the mixture into the prepared tin and smooth the surface.

Step 10

Bake for 30-40 minutes, or until a skewer comes out clean when inserted in the centre.

Step 11

Set aside for 5 minutes, then turn onto a wire rack to cool.