Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.
In a large mixing bowl, whisk together the flour, sugar, baking powder, cinnamon, nutmeg, and salt until well combined.
In a separate bowl, beat the eggs, then stir in the pumpkin and vegetable oil until smooth.
Pour the wet mixture into the dry ingredients and fold gently until just combined, avoiding overmixing to keep the muffins tender.
Spoon the batter into the prepared muffin tin, filling each cup about ¾ full.
To make the streusel topping, combine brown sugar, flour, and granulated sugar in a small bowl. Dice the cold butter and cut it into the dry mixture using a pastry cutter or fork until crumbly.
Sprinkle the streusel evenly over the muffin batter.
Bake the muffins in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out clean and the tops are golden brown.
Remove the muffins from the oven and let them cool for a few minutes before transferring to a wire rack to cool completely. The streusel will be crisp and the muffins moist and fluffy inside.
