Ingredients:

  • 1 ½ cups All-Purpose Flour (for Crumb Topping)
  • ½ cup packed Light Brown Sugar (for Crumb Topping)
  • ¼ cup Granulated Sugar (for Crumb Topping)
  • 2 teaspoons Ground Cinnamon (for Crumb Topping)
  • 8 tablespoons (1 stick) cold, cubed Unsalted Butter (for Crumb Topping)
  • 2 ¼ cups All-Purpose Flour (for Cake Batter)
  • 2 teaspoons Baking Powder
  • ½ teaspoon Baking Soda
  • ½ teaspoon fine sea Salt
  • 8 tablespoons (1 stick) softened Unsalted Butter (for Cake Batter)
  • 1 ¼ cups Granulated Sugar (for Cake Batter)
  • 2 Large Eggs (room temperature)
  • 1 teaspoon Vanilla Extract
  • 1 cup full-fat Sour Cream (room temperature)
  • 1 cup sifted Confectioners’ Sugar (for Glaze)
  • 2–3 tablespoons Milk or Cream (for Glaze)
  • ¼ teaspoon Vanilla Extract (for Glaze)

Instructions:

  1. Preheat the oven to 350°F (175°C). Grease and line a 9x9 inch baking pan with parchment paper, leaving an overhang.
  2. Prepare the Crumb Topping: Whisk together 1 ½ cups flour, brown sugar, ¼ cup granulated sugar, and cinnamon. Add the cubed, cold butter. Use a pastry cutter or your fingertips to cut the butter into the dry mix until large, distinct clumps form. Set aside.
  3. Combine Dry Cake Ingredients: In a separate large bowl, whisk together 2 ¼ cups flour, baking powder, baking soda, and salt.
  4. Cream Butter and Sugar: In the bowl of a stand mixer, cream the softened butter (8 tablespoons) and 1 ¼ cups granulated sugar together on medium speed until light and fluffy (about 3–4 minutes).
  5. Add Eggs and Vanilla: Beat in the 2 eggs, one at a time, mixing well after each addition. Stir in 1 teaspoon vanilla extract.
  6. Incorporate Wet and Dry: Reduce the mixer speed to low. Alternate adding the flour mixture and the sour cream (in three additions of flour and two of sour cream), beginning and ending with the flour. Mix only until just combined. Avoid overmixing.
  7. Assembly: Scrape the batter into the prepared baking pan and spread evenly. Evenly scatter the prepared crumb topping over the entire surface. Press gently to adhere slightly.
  8. Bake: Bake for 45–50 minutes, rotating the pan halfway through. The cake is ready when a toothpick inserted into the center comes out with moist crumbs attached.
  9. Cool: Transfer the pan to a wire rack. Let the cake cool in the pan for 15 minutes before using the parchment overhang to lift it out onto the rack completely.
  10. Prepare Glaze: While the cake is cooling, whisk together the confectioners’ sugar, milk/cream (2–3 tablespoons), and ¼ teaspoon vanilla extract until smooth. Adjust liquid to achieve a thick, drizzling consistency.
  11. Finish and Serve: Once the cake is fully cooled (or at least lukewarm), drizzle the glaze generously over the top. Slice and serve.