Make the sponge by mixing ingredients in bowl and letting sit for 1/2 hour.
In a standing mixer, fitted with a dough hook, add the sponge. Add in the flour, egg, egg yolks, salt, and sugar. Add any additional flour to make smooth dough. Place in oiled bowl, cover and set aside until doubled in volume. Punch down and let rise (covered) again.
Punch down and roll out into a rough triangular shape that is about 1 1/2 feet and 1/2-inch thick. Paint with melted butter. Mix together sugar, cinnamon and hazelnuts. Sprinkle on. Roll up and press into well-buttered bundt pan. Let rise until doubled.
Preheat oven to 375 degrees F.
Bake for 40 minutes. Let cool then remove from pan. Cook together butter, sugar, honey, and liqueur. Paint on top. Sprinkle with nuts.