Turn your oven to 350° F. Butter a 9" springform pan and line it with parchment paper.
Crush the zest into the sugar with your fingers until evenly distributed.
Core and cut the pears into 1" pieces with the skins on. Put them in a bowl. Pour lemon juice over them, toss, and let sit.
In another bowl, whisk together flour, baking powder, baking soda, and salt.
In yet another (large) bowl, crack the eggs. Whisk with the sugar until pale and expanded in volume, then whisk in the olive oil until nice and smooth. Add almond extract and whisk some more.
Dump in the juicy pears, then sift the flour mixture on top of them. Fold them both into the egg mixture. Stop right when the flour disappears.
Scrape the raw cake into the pan, even it out, and bake for an hour. It should be dark brown and smell good; a toothpick poking it should come out clean. (You might need more time. You might also need foil to cover the top if it looks like it's about to burn.) After 30 minutes on a wire rack, the cake can be unbuckled. Let it cool to body temperature, a couple of hours.
Cut the cake with a bread knife. Leftover slices are excellent with or without 10 minutes in a 350° F oven.