01 - Set oven temperature to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease lightly.
02 - Combine flour, brown sugar, cinnamon, and salt in a small bowl. Add cold butter and mix using fingers or a pastry cutter until coarse crumbs form. Refrigerate the mixture until ready to use.
03 - Whisk together flour, matcha powder, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg in a medium bowl.
04 - In a separate large bowl, whisk pumpkin purée, granulated sugar, brown sugar, eggs, vegetable oil, milk, and vanilla extract until fully smooth.
05 - Add the dry ingredients to the wet mixture. Fold gently just until incorporated to avoid overmixing.
06 - Divide the batter evenly among prepared muffin cups, filling each about three-quarters full.
07 - Sprinkle the streusel topping generously over each muffin portion.
08 - Place the muffin tin in the oven and bake for 20 to 22 minutes, or until a toothpick inserted into the center emerges clean.
09 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool fully before serving.