Preheat the oven to 350°F (180°C). Butter a 9-inch (23 cm) round cake pan.
In a medium bowl, whisk together ¾ cup of the sugar and the olive oil. Add the eggs, one at a time, beating well with a rubber spatula after each addition. Add the lemon zest, salt and nutmeg. Stir to combine. Sift in the flour and baking powder. Stir until just combined
Transfer the batter to the prepared pan. Use a spatula to spread it in an even layer. Place the pears, cut side up, in the batter, but don’t press them in more than about ½ inch, as the batter will rise as it bakes. Sprinkle the remaining 1 tbsp of sugar on top. Bake for 30 to 32 minutes, until golden brown and a toothpick inserted into the centre comes out clean. Let cool in the pan for a few minutes before serving.
Cut the cake into squares and serve with a scoop of vanilla ice cream, if desired. Store leftovers in an airtight container in the fridge for up to 4 days.