In a stand mixer add the softened butter and the sugars and mix well.
Add the pumpkin puree, vanilla and eggs and beat until smooth.
Scraping sides of bowl to incorporate all.
In a small bowl whisk the gluten free flour, spices, baking soda, baking powder, salt, oats and nuts.
Alternately add the dry ingredients with the buttermilk and mix on medium speed until well blended.
Fill lined muffin cups 1/3 full with the muffin batter.
Drop 2 Tbsp of cream cheese filing into centre of batter.
Top with remaining batter. (I like to fill the muffins 3/4 full)Top each muffin with a streusel topping (about 2 Tbsp each).Bake in oven for 20-25 minutes until toothpick inserted into muffin comes out clean.
Remove from oven and cool.