Apple Bread Pudding

Name: Apple Bread Pudding
Ingredients: 1 lb. challah bread, cut into 1 cubes (about 12 c.); 3 large eggs; 2 large egg yolks; 3/4 c. (160 g.) light brown sugar, divided; 1 1/2 c. heavy cream; 1 1/2 c. whole milk; 1 tbsp. pure vanilla extract; 1 tsp. ground cinnamon; 1/2 tsp. plus 1/8 tsp. kosher salt, divided; 3 tbsp. unsalted butter, plus more for dish; 1 1/2 lb. Granny Smith apples (about 3 medium), peeled, cored, cut into 3/4 cubes; 1/2 c. dark raisins; 2 tbsp. turbinado sugar (optional)