In a large mixing bowl, add your sugars and oil and mix well with a whisk. You can also use a hand mixer or a stand mixer to mix these up. Just remember to not overmix the batter.
Add your eggs and vanilla and continue to whisk together.
Next, add your sourdough and pumpkin and continue to mix.
Next add your spices, baking powder, baking soda, salt and flour (your dry ingredients) and fold and stir these ingredients in using a rubber spatula. You do not want to overmix the muffin batter.
Preheat your oven to 375 degrees and prep your muffin tin. Use paper liners or spray your pan with nonstick spray. I prefer to do muffin liners.
Scoop 2-3 tablespoons of batter into the liners in the muffin cups. You want to fill them to about 2/3 full
Mix up the flour, sugars, flour and melted butter to create the streusel. Mix together using a fork.
Sprinkle some crumble over the top of each muffin. Be aware that if you add way too much it will prevent the muffin from rising all the way and it may fall into the muffin instead of staying on top.
Bake in the oven for 25 minutes or until a toothpick comes out clean.
Let the muffin pan cool on a wire rack for 10 minutes before removing and for at least 30 minutes before eating.
Store the leftover muffins in an airtight container. You can put them in the fridge or leave on the counter. You can also freeze these!