• Preheat the oven to 350°F (180°C) and grease an 8x8-inch baking pan or line with parchment paper. Set aside.

To Make the Apple Cake:

• In a large bowl, whisk together the dark brown sugar, vegetable oil, and applesauce until combined. Add the milk and vanilla extract and whisk again until well combined.
  180 g dark brown sugar, 40 g vegetable oil, 30 g applesauce, 130 g milk, 1 teaspoon vanilla extract
• Using a silicone spatula, stir in the flour, cinnamon, baking soda, and salt until just combined.
  170 g all-purpose flour, 1 teaspoon ground cinnamon, ½ teaspoon baking soda, ¼ teaspoon fine sea salt
• Add the apples and stir until evenly incorporated. Transfer the batter to the prepared pan and set aside.
  180 g apples

To Make the Streusel Topping:

• In a small bowl, whisk together the dark brown sugar, flour, cinnamon, and salt.
  55 g dark brown sugar, 30 g all-purpose flour, ¼ teaspoon ground cinnamon, pinch of salt
• Add the softened butter and, using a fork, mix until well combined and crumbles form. Sprinkle on top of batter in an even layer.
  30 g unsalted butter
• Bake the cake for 27-30 minutes or until a toothpick inserted comes out clean and relatively crumb-free. Remove cake from oven and let cool while you make the vanilla glaze.

To Make the Vanilla Glaze:

• Add powdered sugar, milk, and vanilla to a small bowl and whisk until well combined and smooth. If the icing is too thin, add a little more powdered sugar; if it's too thick, add more milk. Drizzle glaze over warm cake and enjoy!
  60 g powdered sugar, 15 g milk, ½ teaspoon vanilla bean paste