Preheat oven to 350 degrees. Spray an 8 inch round cake pan with non-stick spray or grease with butter.

Add chocolate and butter to a heatproof bowl over barely simmering water (double boiler) making sure the bowl is not touching the water. Stir until fully melted and combined. Remove from heat to allow to cool for a minute or two.

Add hazelnut spread to the melted chocolate mixture and mix well.

In a medium mixing bowl whisk together eggs, sugar and vanilla.

Add chocolate mixture to the egg mixture and stir to combine.

Sift flour and baking powder into the chocolate mixture, stirring just until no streaks of flour remain. Pour into prepared pan and bake for 30-40 minutes. Checking for doneness at 30 minutes, bake until toothpick inserted in centre comes out clean. Allow to cool completely (about 1 hour).

Prepare ganache; Chop chocolate for the ganache into small pieces and add to a heatproof bowl. Heat cream over medium heat just until small bubbles appear around the edges of the pot. Do not bring to a boil. Pour hot cream over chocolate and allow it to sit for 30 seconds. Begin stirring mixture until fully combined and smooth. Allow to cool for 10-15 minutes, cover surface with plastic wrap and refrigerate for at least 30 minutes to allow it to thicken.