Pear and Chocolate Brioche Bread Pudding

INGREDIENTS

• Unsalted butter, room temperature, for baking dish
• 3 ounces bittersweet chocolate, coarsely chopped
• 7 ounces brioche, cut into eight 1/2-inch slices, halved diagonally
• 1 1/2 pounds firm but ripe pears, such as Anjou or Bartlett (about 3), cored and very thinly sliced
• 3 large eggs, plus 3 large egg yolks
• 1 1/2 cups whole milk
• 1 1/4 cups heavy cream
• 1/2 cup packed light-brown sugar
• 1 teaspoon ground cinnamon
• 1/4 teaspoon fine salt
• 1 tablespoon sanding or other coarse sugar