Heat oven to 425°F. Grease a standard 12-cup muffin tin (or line it with papers). I have tried bigger muffins but they don't cook evenly and so end up underdone inside.

Get a large mixing bowl. Halve and core your pears, then either dice them (bite-size) or you can grate them on the large holes of a box grater (I diced). Technically you should have about 1 cup grated or closer to 1 1/2 diced, but I don't worry too much about the amounts.

Stir in melted butter, sugar, buttermilk, eggs and vanilla until combined. Then add the two types of flour, oats, spices, baking soda, baking powder, and salt. Gently fold these dry ingredients into the wet batter until just combined; do not overmix. Then add all but 1/2 cup of chopped hazelnuts, and the chocolate chunks and barely stir in.

Fill the muffin cups almost up to the top and sprinkle with turbinado and (if desired) the reserved 1/2 cup of hazelnuts (I chopped mine more finely).

Place muffins in oven and immediately reduce the heat to 375°F. Bake for 18 to 23 minutes, or until the tops are golden brown and a toothpick inserted into the center of muffins comes out batter-free. Start watching them carefully around the 18 minute mark, as baking times will definitely vary based on your muffin tin size.

Let the muffins cool in the pan for 10 minutes, then transfer to a cooling rack. Muffins will keep for 2 days at room temperature in an airtight container.