Ingredients:

  • 1/2 cup (60g) all-purpose flour
  • 1/2 cup (100g) brown sugar, packed
  • 1 tbsp (8g) ground cinnamon
  • 1/4 cup (55g) unsalted butter, cold and cubed
  • 1/2 cup (60g) chopped walnuts
  • 3 cups (375g) all-purpose flour
  • 1 tbsp (12g) baking powder
  • 1/2 tsp (3g) fine sea salt
  • 1 cup (225g) unsalted butter, softened to room temperature
  • 1 1/2 cups (300g) granulated white sugar
  • 3 large eggs, room temperature
  • 2 tsp (10ml) pure vanilla extract
  • 2 cups (480g) full-fat sour cream, room temperature

Instructions:

  1. In a small bowl, whisk together 60g flour, 100g brown sugar, and 8g cinnamon. Use a fork or fingertips to rub 55g cold cubed butter into the mixture until it resembles coarse wet sand. Stir in walnuts and refrigerate.
  2. Preheat oven to 350°F (175°C) and grease a 10-inch Bundt pan or 9x5 inch loaf pan.
  3. In a medium bowl, whisk together 375g flour, 12g baking powder, and 3g salt.
  4. In a large bowl, beat 225g softened butter and 300g white sugar on medium-high until light and fluffy (3-5 minutes). Add eggs one at a time, beating well after each, then stir in vanilla extract.
  5. Lower mixer speed. Add half of the flour mixture, then half of the room-temperature sour cream. Repeat with the remaining flour and sour cream until just combined; do not overmix.
  6. Pour one-third of the batter into the pan. Sprinkle a layer of streusel, followed by another third of batter, more streusel, and the final third of batter. Top with the remaining streusel.
  7. Bake for 55-65 minutes until a toothpick inserted into the center comes out clean or with a few moist crumbs.