Double Chocolate Croissant Bread Pudding

Name: Double Chocolate Croissant Bread Pudding
Ingredients: 4 tablespoons unsalted butter, melted, plus more for the dish; 8 large croissants, sliced 1 inch thick (about 12 cups); 3 large eggs plus 3 egg yolks; 1 ½ cups whole milk; 1 cup heavy cream; ¼ cup sugar; 1 teaspoon pure vanilla extract; pinch of salt; 6 ounces milk chocolate, cut into ¾ inch pieces; 1/3 cup heavy cream; 2 tablespoons unsalted butter; 2 tablespoons sugar; 2 tablespoons light corn syrup; 4 ounces bittersweet chocolate chopped