Glazed Mocha Fudge Cake

185g butter
2 tsp vanilla essence
1 1/2 cups caster sugar
4 eggs separaqted
3/4 cup SR flour
1/3 cup cocoa
3/4 cup plain yogurt
3 tsp instant coffee (dry)
1tbls boiling water

Glaze-
60g dark chocolate
30g butter
1tsp instant coffee
3/4 cup icing sugar.

Grease and paper then grease paper a square slab pan.
Cream butter, essence and sugar in a small bowl until fluffly. 
Beat in eggs yolks 1 at a time.  Beat only until combined. 
Stir in sifted flour and cocoa and yogurt then combined coffee and water.
Beat egg whites in a small bowl until soft peaks, lightly fold through cake mixture in 2 lots. 
Pour mixture into pan and bake in mod oven for 45 mins.  Cool and top with glaze...refridgerate until glaze is set.

Glaze-
Combine chocolate, butter and combined coffee and water in a saucepan, stir constantly over low heat, without boiling, until smooth.  Remove from heat, gradually stir in sifted icing sugar.