Grate chocolate coarsely and mix with nuts. Separate the eggs. Mix flour with baking powder and cinnamon.
Cream butter with sugar until creamy. Stir in yolks one by one. Add chocolate and nut mixture. Sift in flour mixture. Gently stir to combine. Beat egg whites with salt until stiff and fold into batter.
Grease baking dish with butter and pour in batter. Bake in a preheated oven at 200°C (approximately 400°F) for about 35-40 minutes. Cake is done when toothpick inserted in center comes out clean. Let rest for 10 minutes in baking dish before flipping onto a wire rack to cool completely. Heat glaze according to package instructions and pour over cake. Dry, slice and serve.