Preheat your oven to 350°F (175°C). Line a muffin tin with paper liners or lightly grease each cup to prevent sticking.
In a medium mixing bowl, combine the softened cream cheese and powdered sugar. Use a hand mixer to beat them together until smooth and creamy. Set aside.
In a large mixing bowl, whisk together the pumpkin puree, brown sugar, granulated sugar, vegetable oil, eggs, and vanilla extract until smooth.
In a separate bowl, sift together the all-purpose flour, baking powder, baking soda, pumpkin spice, and salt.
Gradually add the dry mixture to the wet ingredients. Stir gently until just combined.
If using nuts, gently fold the chopped walnuts or pecans into the batter.
Spoon about 2 tablespoons of the pumpkin muffin batter into each muffin cup. Add approximately 1 teaspoon of the cream cheese mixture in the center of each muffin, then top with more pumpkin batter.
Bake for 20-25 minutes, checking for doneness with a toothpick.
Let the muffins cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.
Notes
Serve warm and dust with powdered sugar for an elegant touch.