Beat pumpkin, eggs, sugar, butter, and vanilla by hand or in the bowl of your mixer until fully combined.
1 stick butter, ¾ cup firmly packed light brown sugar, 1 cup pumpkin puree, 2 large eggs, 1 ½ teaspoons vanilla extract
Alternately add buttermilk and dry ingredients to pumpkin mixture just until all ingredients are combined. (Some small lumps are okay.)
¾ cup buttermilk
Divide batter into muffin cups, filling each cup just over ½ way. Use a spoon to top each muffin with about one tablespoon of the cream cheese mixture. Push cream cheese into the batter slightly. Sprinkle muffins with pumpkin seeds and place in oven.
¼ cup green pumpkin seeds
Bake for 18-20 minutes. A toothpick inserted in muffin (not cream cheese center) should come out clean.
Remove pumpkin muffins from tins and cool on a rack for 10 – 15 minutes.
Notes
If you're using a stand mixer, there's no need to wash the bowl in between the two stages. Simply use a spatula to transfer the filling to another bowl, then proceed to mix the remaining ingredients. Nobody will know, and you'll have fewer dishes to wash.