Irish Brown Bread Ice Cream with Butterscotch Sauce

Ingredients

• Unsalted butter, for greasing
• 3⁄4 cup all-purpose flour, plus more for the pan
• 1 tsp. baking soda
• 3⁄4 tsp. kosher salt
• 3⁄4 cup plus 2 Tbsp. whole-wheat flour
• 1⁄4 cup plus 2 Tbsp. wheat bran
• 1⁄4 cup wheat germ
• 1⁄4 cup steel-cut oats
• 1 tbsp. dark brown sugar
• 1 cup buttermilk
• 1 1⁄2 tsp. sunflower or vegetable oil
• 1 cup whole milk
• 1 vanilla bean, halved lengthwise
• 1⁄2 cup plus 1 Tbsp. sugar
• 4 large egg yolks
• 2 cups plus 2 Tbsp. heavy cream
• 1⁄4 cup plus 1 Tbsp. packed dark brown sugar
• 5 cups finely crumbled Irish brown bread, preferably 1–2 days old
• 1 1⁄4 cups heavy cream
• 1 cup dark brown sugar
• 1⁄4 cup salted butter
• 1 tsp. kosher salt
• 1⁄2 tsp. vanilla extract