Preheat the oven to 350 degrees. Line muffin pans with paper liners.
For the filling, combine the cream cheese and powdered sugar in the bowl of an electric mixer; whip until smooth. Form into a log on plastic wrap or foil, making sure that the diameter is small enough to fit into the well of a muffin pan. Wrap the log up tightly and freeze until firm, 1 to 2 hours.
For the muffins, combine the flour, spices, salt and baking soda in a medium bowl. Mix well and set aside. In the bowl of an electric mixer, combine the eggs, vegetable oil, sugar and pumpkin puree. Mix until well combined. Add in the dry ingredients and mix on low speed until just combined.
For the topping, combine all ingredients in a small bowl. Mix together with a pastry blender or two forks until crumbly.
To assemble the muffins, fill each muffin well halfway with batter. Remove the cream cheese log from the freezer and slice into 24 equal slices. Place a slice in each muffin well. Divide the remaining muffin batter evenly among the muffin cups, on top of the cream cheese. Sprinkle the streusel topping, and a few seeds if desired, over the top of the batter. Bake for 20 to 25 minutes. Let cool completely before serving.