01 - In a large bowl, combine bread flour, sourdough starter, water, and salt. Mix until a shaggy dough forms. Cover and rest for 30 minutes.
02 - Perform 2-3 sets of stretch and folds over the next 1.5 hours, resting 30 minutes between each. After the last fold, cover and refrigerate the dough overnight for 8-12 hours.
03 - Generously oil a 9x13-inch baking pan. Transfer the dough to the pan, stretching it out gently to fit. Let it rise, covered, at room temperature for 2-3 hours until very puffy.
04 - Beat cream cheese, sugar, egg yolk, vanilla, and lemon zest in a medium bowl until smooth and creamy.
05 - Toss raspberries with sugar and lemon juice. Set aside to macerate.
06 - Preheat oven to 425°F.
07 - With oiled fingers, dimple the focaccia dough. Dollop the cheesecake mixture evenly over the top, then gently swirl with a knife or spatula. Scatter raspberries and their juices over the dough.
08 - Drizzle a little more olive oil over the surface. Bake for 25-30 minutes until golden brown, set, and the edges are crisp.
09 - Let cool at least 30 minutes before slicing. Serve warm or at room temperature.