Preheat oven to 350°F. Grease two 9x5-inch loaf pans; set aside.
Sift the flours, arrowroot, baking powder, baking soda, psyllium husk, spices, and salt into a large mixing bowl, then whisk until thoroughly combined; set aside.
In another large bowl, whisk together the oil and sugars until the mixture appears sandy, then add the eggs and whisk until combined. Whisk in the pumpkin puree and the vanilla until combined.
Using a rubber spatula, add the dry ingredients into the wet in 3 applications, until the mixture is smooth.
Fold in the diced pears and chocolate chunks.
Evenly divide the batter between the two prepared loaf pans, top with the chopped walnuts, then arrange a half pear’s worth of slices on the top of each loaf.
Bake for 35-40 minutes, until a cake tester inserted into the center of the cake comes out clean. remove the bread and place it on a rack to cool for roughly 30 minutes.
Remove the bread from the pan; let it cool completely before slicing.