Preheat to 350°F (175°C). Grease and line a loaf pan (8×4 or 9×5) with parchment.
Coarsely grate pears and lightly blot with a paper towel so the batter stays moist, not soggy.
In a large bowl whisk coconut sugar, oil, eggs, vanilla, and orange zest until smooth. Stir in the grated pears. Leave some out to place on top of the bread (optional)
In a separate bowl whisk all-purpose flour, rye flour, ground flaxseed, baking soda, baking powder, cinnamon, nutmeg, and salt and roughly chopped hazelnuts
In a small bowl combine coconut sugar, flour, and cinnamon. Cut in the cold butter with a fork (or fingers) until crumbly, then stir in the remaining ½ cup hazelnuts.
Spread batter into the pan, top with the shredded pears and sprinkle streusel evenly over the top. Bake 45–55 minutes, until a toothpick in the center comes out with a few moist crumbs. If the top browns too quickly, tent with foil for the last 10–15 minutes.
Cool in the pan 10 minutes, then lift out to a rack to cool completely before slicing.
Notes
Use grated pears, not chopped - they melt into the batter, keeping it moist and evenly flavored. Don’t overmix the batter - once the dry and wet ingredients are combined, stop stirring. Keep the butter cold for streusel - cold butter is essential for a crumbly, crunchy topping.