In a large bowl, dissolve yeast in warm water. Add cream, milk, sugar, butter, Nutella, hazelnut syrup, salt, espresso powder and 2 cups flour; beat on medium speed until smooth. Stir in enough remaining flour to form a soft dough (dough will be sticky).
Turn dough onto a floured surface; knead until smooth and elastic, 6-8 minutes. Place in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 45 minutes.
Punch dough down. Turn onto a lightly floured surface. Roll into a 20x16-in. rectangle. Combine filling ingredients until smooth. Spread over dough to within ½ in. of edges. Roll up jelly-roll style, starting with a short side; pinch seam to seal. Cut into 8 slices. Place in a greased or parchment-lined 13x9-in. baking pan. Cover and refrigerate overnight.
Remove from refrigerator; cover and let rise in a warm place until almost doubled, about 45 minutes.
Preheat oven to 350°. Bake until golden brown, 25-30 minutes. Meanwhile, combine confectioners' sugar, butter, buttermilk and hazelnut syrup until smooth. Drizzle over warm rolls. Sprinkle with hazelnuts if desired. Serve warm.
