Move the oven rack to the middle position. Preheat the oven to 425°F (220°C). Grease two muffin pans with nonstick spray or line them with muffin papers. Set aside.

In a large bowl, whisk together the 2 cups all-purpose flour, 1 teaspoon ground cinnamon, 1 teaspoon ground nutmeg, 1 teaspoon baking soda, and 1 teaspoon kosher salt until well combined.

In a separate bowl, add the 1 15 oz can pumpkin puree. 1 cup sourdough discard, ¾ cup brown sugar, ½ cup neutral oil, 2 large eggs, and 2 teaspoons vanilla extract. Whisk to combine.

Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; a few lumps are fine.

Divide the muffin batter evenly among the muffin cups filling halfway.

In a small bowl, add the 8 oz cream cheese, ⅓ cup granulated white sugar, ½ teaspoon vanilla extract, and ⅛ teaspoon kosher salt. Mix together until smooth.

Add 2 teaspoons of the cream cheese filling to the center of each muffin. Top with the remaining pumpkin muffin batter.

In a small bowl, add the ¼ cup all-purpose flour, ¼ cup pepitas or pumpkin seeds, ¼ cup old-fashioned rolled oats, ⅛ cup brown sugar, 1 teaspoon ground cinnamon, and 4 tablespoons unsalted butter. Use a fork to stir all of the ingredients together.

Sprinkle the streusel over each muffin.

Bake the muffins in the preheated oven for 5 minutes, then, keeping the muffins in the oven, reduce the oven temperature to 350°F (180°C) and continue to bake for 20 to 24 minutes until the tops are golden brown.

Allow the muffins to cool for several minutes in the muffin pan before transferring them to a wire rack to cool completely.