Preheat your oven to 400°.
Line your muffin pan with cupcake liners.
In a large bowl, combine the carrot cake mix with pure pumpkin until well blended.
In another bowl, combine the flour, brown sugar, granulated sugar, cinnamon, and cold butter cut into small pieces. Mix until crumbly.
Spoon the pumpkin mixture into each muffin liner until they're about two-thirds full. Sprinkle with the streusel topping.
Bake for about 20 minutes or until golden brown and a toothpick comes out clean.
Let the muffins cool in the pan for about five minutes before transferring them to a wire rack.