Preheat oven to 350° F. Prepare syrup by simmering sugar, maple syrup, water and cinnamon sticks for 10 minutes. Remove from heat and stir in hazelnut liqueur. Add hazelnuts and let soak for 3 minutes (just to absorb a little sweetness). Strain off liquid and pour it into an 8-inch square baking dish. Roughly chop soaked hazelnuts and spread on a parchment lined baking sheet. Toast in the oven for 6 to 8 minutes, until golden brown.
While hazelnuts are toasting prepare pears. Peel pears halfway down and scoop out core from the bottom, using a melon ball scoop. Using ¾ cup of chopped hazelnuts, fill each pear. Place pears in syrup. Roast pears for 20 minutes, until they are soft when pierced with a tester.
To serve, place pear on a plate, drizzle syrup over and sprinkle generously with hazelnuts.