Apple Rum Raisin Bread Pudding - Once Upon a Chef

Ingredients

• ⅔ cup raisins
• 2 tablespoons dark or spiced rum
• 4 large eggs
• 2 cups whole milk
• 1 cup sugar
• 3 tablespoons unsalted butter, (melted and slightly cooled)
• ½ teaspoon ground cinnamon
• ¼ teaspoon salt
• ½ teaspoon vanilla
• 4 cups packed challah or brioche cubes, (from one loaf with crust removed (you won't use entire loaf))
• 1 large tart baking apple ((such as Granny Smith), peeled, cored, cut into ⅛-inch (3-mm) slices and then cut in half)
• Vanilla ice cream (for serving)