Preheat the Oven
Preheat your oven to 350°F (175°C).
Line a 12-cup muffin pan with paper liners or lightly grease the cups.
Mix the Dry Ingredients
In a medium bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, and nutmeg.
Combine the Wet Ingredients
In a large bowl, whisk together granulated sugar, brown sugar, and vegetable oil until smooth.
Add eggs, pumpkin puree, milk, and vanilla extract. Mix until well combined.
Combine Wet and Dry Mixtures
Gradually add the dry ingredients to the wet mixture. Stir gently until just combined, being careful not to overmix.
Prepare the Streusel Topping
In a small bowl, mix flour, brown sugar, cinnamon, and melted butter until crumbly.
Fill the Muffin Cups
Spoon the batter into the prepared muffin cups, filling each about two-thirds full.
Sprinkle the streusel topping generously over each muffin.
Bake the Muffins
Place the muffin pan in the preheated oven and bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.
