Lemon Zucchini Snack Cake with Blueberry Swirl

Steps

1. Grate the zucchini, wrap it in a clean towel and squeeze out as much liquid as you can; set aside.
2. Make the berry filling: in a small pot, stir the blueberries, cornstarch, lemon juice and 40 g (about one fifth) of the sugar. Simmer over medium heat, stirring, 5 to 6 minutes until thick and jammy. Spread on a plate to cool for 15 minutes.
3. Preheat the oven to 350°F (175°C). Grease a 9x13-inch pan and line the bottom with parchment.
4. In a medium bowl, whisk the flour, baking powder, baking soda, salt and cinnamon.
5. In a large bowl, rub the lemon zest into 145 g of the sugar with your fingers until fragrant, leaving the last 15 g of sugar for the top. Whisk in the egg until pale, then whisk in the canola oil, Greek yogurt and vanilla.
6. Stir the zucchini into the wet mixture, then fold in the flour mixture just until no dry streaks remain.
7. Spread half the batter in the pan. Dot the cooled blueberry filling over it, then spoon the remaining half of the batter on top and swirl gently with a knife.
8. Sprinkle the reserved 15 g of sugar over the top.
9. Bake 35 to 40 minutes, until golden and a toothpick in the cake (not the berry swirl) comes out clean.
10. Cool in the pan on a rack for at least 1 hour, then cut into 12 slices.