Preheat the oven to 350°F (180°C.) Grease and line an 8-inch round cake pan with 3-inch high sides or a 9-inch round cake pan with parchment paper.
Peel and core the pears and then slice them into ¼-inch slices. Add them to a medium bowl. Toss them with ½ tablespoon of lemon juice.
Whisk together the flour, baking powder, and salt in a small bowl and set aside.
Whisk melted butter, oil, sugar, vanilla, and eggs in a large bowl until combined.
Fold the dry ingredients into the wet ingredients and the milk until combined. There may be a few small lumps of flour, but that's okay.
Pour half the cake mixture into the prepared pan.
Arrange half of the pears over the batter, snuggly fitting and overlapping them on. Spoon over the remaining cake batter and top with the remaining pear slices.
Sprinkle the top of the batter with the extra sugar.
Bake the cake for 45-55 minutes until golden brown and a skewer inserted in the middle comes out clean.
Let the cake cool for 10 minutes before removing from the pan. Use a knife to loosen the edges, flip the cake onto a wire rack, remove the paper, then flip it onto another rack to finish cooling to room temperature.
Transfer to a serving plate and dust with powdered sugar before serving.