Prepare oven and muffin pan: Preheat oven to 375 F degrees. Line a 12-cup muffin pan with paper liners and spray each liner with cooking spray. This will ensure paper liners come off smoothly from muffins.
Prepare streusel topping: First prepare the streusel topping by combining the 2 tbsp of flour with the tbsp of brown sugar, breaking the sugar with a fork. Add the butter and stir in with a fork, or use your fingers to crumble up the mixture. Set aside.
Prepare muffin batter: To prepare the muffin batter, first combine the flour, baking powder, baking soda, cinnamon, ginger, allspice and salt in a large bowl. Whisk to combine properly.
In another bowl add the eggs, applesauce, buttermilk, the sugars, vanilla extract and whisk well or use your mixer to mix properly. Using a spatula stir in the flour mixture. Stir in the grated carrots.
Fill muffin cups with batter: Using an ice cream scoop, divide the batter equally among the 12 cups.
Top muffins with streusel: Sprinkle each muffin with some of the streusel topping and the pepitas.
Bake: Bake for 20 minutes or until muffins are done. To test for doneness, insert a toothpick in the center of a muffin and if it comes out clean the muffins are baked.
Cool and serve: Cool in the pan for 10 minutes then remove and serve.