Preheat the oven to 350°F.
Grease and flour a 9-inch round cake pan. (Note 2)
In a small container such as a liquid measuring cup, stir together the milk, oil, lemon juice, vanilla extract and lemon zest.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, salt and cinnamon.
Pour the milk mixture into the bowl with the flour mixture and stir everything together until combined.
Fold in the diced pears.
Transfer the batter to the prepared cake pan.
Bake the cake for about 38 to 43 minutes, or until it is golden brown on top and a toothpick inserted into the center comes out clean of batter.
Transfer the cake to a cooling rack and let it cool completely before removing it from the pan. (Note 3)
Optionally, dust the cake with powdered sugar. Slice and serve.