• Preheat oven to 350℉. Spray a 9 inch springform pan with cooking spray and set aside. (If using a 9 inch round cake pan, line the bottom of the pan with parchment paper and spray the sides with cooking spray. Place two long strips of parchment paper in an X shape across the inside and up the sides of the pan; these will be used for helping to lift the cake out of the pan.)

Make the cake batter.

• In a large bowl, whisk together the flour, baking powder, and salt.
  2 cups all-purpose flour, 1 Tablespoon baking powder, 1 teaspoon fine sea salt
• Using a pastry cutter, cut the cold, cubed butter into the flour mixture until the mixture resembles cornmeal.
  4 Tablespoons unsalted butter
• Add oats, brown sugar, and cinnamon and whisk to combine.
  ⅔ cups old-fashioned oats, 2 Tablespoons light brown sugar, ½ teaspoon ground cinnamon
• In a small bowl or large measuring cup, whisk together egg and milk. Add the liquid ingredients to the dry ingredients and stir just until combined. Set aside.
  1 large egg, 1 cup whole milk

Make the crumb topping.

• In a medium bowl, whisk to combine oats, brown sugar, and cinnamon.
  1 cup old-fashioned oats, ⅔ cup light brown sugar, ½ teaspoon ground cinnamon
• Add melted butter and toss together with a fork until a crumbly mixture forms. Set aside.
  4 Tablespoons unsalted butter

Bake the cake.

• Spread half of the cake batter over the bottom of the pan. Sprinkle half of the crumb topping over the batter. Scatter ¾ cup (113 grams) of the blueberries over the crumb topping.
• Spread the remaining batter over the topping and blueberries.
• Slice peaches into quarters, then quarter again (you should have 20 wedges). Lay the peach wedges over the top of the cake batter. Scatter the remaining ½ cup (75 grams) of blueberries over the peach slices. Sprinkle the remaining crumb topping over the fruit.
• Bake the cake for 30-35 minutes or until a toothpick inserted into the center of the cake comes out clean or with a few moist crumbs (but no raw batter). Run a cake tester or knife around the inside of the pan to loosen the edges of the pan. Let the cake cool in the pan on a wire rack before removing.

Make the glaze.

• In a small bowl, whisk together the confectioners' sugar and milk. The mixture should be thick but pourable. Spoon the glaze over the cake.
  2 Tablespoons confectioners' sugar, ½ teaspoon whole milk