Preheat your oven to 350F. Slice the pears and set aside. In a large bowl or stand mixer, beat the eggs until they've lost their orange color and have become a bit paler, about 1 minutes
Add to the mix the juice of two oranges and the zest from one and whisk lightly. Now add the flour, spice mix, baking powder, sugar, vanilla and salt and mix completely.
Once those ingredients are incorporated, slowly add the oil as you mix the batter. The result will be rather thick, sticky, and perfect for what is next.
Grease and flour a 10-inch tube pan. Take about a third of the batter mixture and lay down a nice coating on the bottom of the pan. This will actually be your top, so you want to make sure you've made a thick layer all the way around the base of the pan.
Lay pear slices on top of your batter layer. Add another layer of batter and another layer of pear slices. You should get between 2-3 layers of pears. The final layer should be batter.
Place your pan in the oven and bake for approximately 90 minutes. To check for doneness, insert a toothpick in the middle and remove it. It should come out clean when the cake is done. Remove finished cake from the oven and leave it in its pan for at least 30 minutes. on a rack or other tray.
Once sufficiently cool, you can turn it out onto a plate or simply leave it in its pan and cut slices from it. In either case, be sure to work slowly. Sprinkle slices with confectioners sugar and enjoy!