In a saucepan, melt butter over low heat. Remove from heat and add milk and half of the orange zest.
In a large bowl or the bowl of a stand mixer, beat eggs with sugar until pale and fluffy. Add the contents of the pan and mix thoroughly.
Mix or finely chop 80 g of whole hazelnuts.
In a separate bowl, combine the flour, hazelnut powder and baking powder. Sift the dry ingredients over the first mixture and gently fold in with a spatula, taking care not to overwork the dough in order to keep it light and fluffy.
Oil or butter the pan, concentrating on the corners, and lightly flour it. Remove excess flour, pour in the dough and level the surface.Bake in the oven at half height for 40 minutes. Monitor the cooking and remove the cake from the oven when it is golden brown and a sharp knife tip comes out dry. Let it cool for 5 minutes in the pan before gently unmolding it.
Preparing the honey glaze:
Coarsely chop the remaining 20 g of hazelnuts and lightly toast them in a dry pan.
In a saucepan, melt the honey over low heat and add half of the roasted hazelnut slivers and the rest of the orange zest, keeping the equivalent of a teaspoon for decoration. Remove from the heat as soon as the honey starts to simmer and let it infuse.
Final touch:
Place the cake on the serving platter and spoon the honey glaze generously over the top of the crown. Sprinkle with remaining toasted hazelnut chips and orange zest and serve warm :)