Ingredients:

  • 165g brown sugar, packed
  • 100g gluten-free all-purpose flour blend (containing xanthan gum)
  • 12g ground cinnamon
  • 85g unsalted butter, cold and cubed
  • 1g sea salt
  • 280g gluten-free 1-to-1 flour blend
  • 200g granulated white sugar
  • 10g baking powder
  • 3g baking soda
  • 2g salt
  • 240g full-fat sour cream
  • 115g unsalted butter, melted and cooled
  • 2 large eggs, room temperature
  • 10ml pure vanilla extract

Instructions:

  1. Prepare the streusel: In a medium bowl, combine 165g brown sugar, 100g gluten-free flour, cinnamon, and sea salt. Use your fingers or a fork to rub the 85g of cold cubed butter into the mixture until distinct, pea-sized clumps form. Place in the refrigerator while preparing the batter.
  2. Whisk the wet ingredients: In a large mixing bowl, combine the 115g melted butter, 200g granulated sugar, eggs, sour cream, and vanilla extract. Whisk until the mixture is completely smooth.
  3. Incorporate dry ingredients: Sift the 280g gluten-free flour, baking powder, baking soda, and salt directly into the wet ingredients. Fold gently with a spatula until no dry streaks remain and the batter is uniform.
  4. Assemble and Bake: Transfer the batter into a prepared 9x9 inch baking pan lined with parchment paper. Distribute the chilled streusel evenly over the top. Bake for approximately 40 minutes at 350°F (175°C) or until a toothpick inserted into the center comes out clean.