Preheat the oven to 425 degrees Fahrenehit.
Add the peeled and chopped carrots to a food processor and process until broken up and completely shredded.
In a large mixing bowl, whisk together all wet ingredients until combined.
Add in the dry ingredients aside from the nuts and carrots and mix well with a wooden spoon. Be sure to spoon and level the flour, don't scoop right from the bag.
Fold in the chopped walnuts and carrots until everything is well incorporated. The batter should be pretty thick at this point, but that is key to a muffin with a nice round top!
Use a spoon or cookie scoop and add the batter to a lined cupcake/muffin tray. Fill about pretty close to the top.
To make the streusel topping, add the softened butter, flour, sugar and cinnamon to a small bowl. Use a fork, your hands or a pastry cutter to combine the ingredients. It should be crumbly and on the drier side. If it seems too wet, add in a bit more flour.
Use your fingers to crumble the streusel on top of the muffins. Add more than you think you should, the streusel will separate as the muffins bake.
Bake at 425 for 2 minutes, then lower the temperature to 350 and bake for 14-18 more minutes. Careful not to over-bake, you don't want them to become dry. Test them at 14 minutes, a toothpick should come out clean, but add about 2 more minutes at a time as needed. 15 is usually perfect in my oven!
Remove from the oven, let cool as is for 10 minutes, then remove the muffins from the tray and let finish cooling on a cooling rack.
Once cool, whisk together the cream cheese and maple syrup and drizzle on top of the muffins.