Preheat the oven to 350° F. Butter an 8 or 9-inch cake pan, cut a piece of waxed paper or parchment paper to fit the bottom and butter the paper too.

Cream the butter and sugar well until light and fluffy: then add the eggs one at a time and continue beating after each until the whole mixture becomes very light.

Whisk the flour, baking powder and salt; at low speed with the mixer fold two thirds of the dry mixture into the creamed butter, sugar and eggs.

Dissolve the instant coffee in the water and add it to the batter; then fold in the remaining 1/3 of the flour.

Spoon the batter into the prepared cake pan, and smooth the top of the batter, leveling it out.

Bake for 25-40 minutes depending on the size of your cake pan, until the cake is just starting to pull away from the sides of the pan. Carefully turn the pan out onto a rack; remove the paper from the bottom and allow to cool. Wash the cake pan and dry carefully; it will be used again.

Heat the strong coffee and sugar together gently until the sugar has dissolved then boil rapidly for 1 minute. Remove the pan from the heat and stir in the Irish whiskey.

Return the cooled cake to the pan and pour the syrup over it; leave it to soak for 2-3 hours.

Whip the heavy cream til soft peaks form. Add the sugar and continue beating until peaks are stiff.

Add the Irish whiskey and gently combine.

Turn the cooled cake out onto a serving plate, decorate with the whipped cream and sprinkle with the chopped/toasted hazelnuts. Chill well before serving.