To make the crumble topping, place the brown sugar, sugar, flour and cinnamon into a medium bowl. Whisk to combine.
To the sugar mixture add your fat of choice and cut it in until pieces are the size of peas. Set aside.
To make the muffin batter, in a large bowl combine flour, sugar, baking powder, salt, and nutmeg. Mix with a whisk to combine.
To the dry ingredients add the milk, oil, and pumpkin puree. Using a spoon or spatula mix until the dry ingredients are just moistened.
Spoon into muffin cups about 3/4 the way full.
Sprinkle the tops with the crumble topping and bake at 400 degrees for about 20 minutes or until muffins are baked through. Test with a toothpick in the center of the muffin, if it comes out clean they are done baking.