1. Preheat oven to 350°F and grease a springform pan.

2. Rub lemon zest into sugar until fragrant, then whisk in flour, salt, baking soda, and baking powder.

3. Add butter, yogurt, eggs, and vanilla. Mix until just combined.

4. Coat blackberries in flour, fold gently into batter, and pour into pan.

5. Bake 30 minutes, rotate, then bake 20–25 minutes more until toothpick comes out clean.

6. Cool 10 minutes, release pan, and let sponge cool completely.

7. Macerate blackberries with sugar and lemon juice. Mash half if fresh, leave thawed if frozen.

8. Whisk yolks, sugar, zest, juice, and salt over simmering water until thick. Add mascarpone spoon by spoon. Chill.

9. Whip cream to soft peaks, fold into chilled curd to make mascarpone cream.

10. Slice sponge into 2 layers. Spread half cream, add macerated blackberries, then top with second sponge.

11. Spread remaining cream on top, swirl in lemon curd, and decorate with blackberries.

12. Chill 1–2 hours before slicing for best results.