Preheat the oven to 180C (350F). Line a 6-hole muffin tray with paper liners. Set aside.
In a medium mixing bowl, mix the softened butter and 1/3 cup granulated erythritol using a handheld mixer until light and creamy. Add the eggs, one at a time, on low speed while scraping down the bowl occasionally to ensure all ingredients are well incorporated.
Add the pumpkin puree and vanilla extract. Mix on low speed until just combined. The consistency will be a bit runny and not as foamy.
Whisk together almond flour, coconut flour, baking powder, pumpkin spice, and salt in a separate mixing bowl. Ensure all the dry ingredients are well incorporated and no lumps are left behind.
Add the dry mixture to the bowl with the wet ingredients. Gently mix with a spatula to fully incorporate all the dry ingredients into the liquid mixture.
In a small bowl, whisk together softened cream cheese and 1 tbsp of powdered erythritol. This mixture will be used to top the muffins as a cream cheese layer before baking them.
Use an ice cream scoop to portion the muffin batter evenly among 6 muffin holes. This ensures that each muffin has the same amount of batter hence an equal amount of carbs per muffin serving. Add about 1 tablespoon of cream cheese to the muffins. Use a toothpick to swirl the batter and cream cheese together.
Transfer the muffins to the oven. Bake for 20 minutes. To confirm whether the muffins are baked through, insert a toothpick at the center of each muffin once the timer is done. The toothpick should come out clean.
Remove from the oven and let the muffins cool down in the tray for about 15 minutes. Then, transfer the muffins onto a cooling rack until completely cooled. Enjoy with a warm cup of tea or coffee.