Before I even touch the blender, I slice my bananas and freeze them ahead of time if they aren't already frozen. I also measure out my pumpkin puree, milk, and spices so everything is ready to go. Having it all prepped makes the blending step almost instant.
I add the pumpkin puree, frozen banana, ground flaxseed, pumpkin pie spice, milk, and vanilla extract into the blender first. I hold off on the sweetener at this point because I like to taste the base before deciding how sweet I want it to be.
I blend everything on high for about 30 to 45 seconds, stopping once to scrape down the sides with my spatula. I'm looking for a completely smooth, creamy consistency with no lumps of banana or pumpkin left behind.
Once it's smooth, I add the brown sugar or maple syrup and blend again for another 10 to 15 seconds. I always taste it at this stage since pumpkin puree brands vary in sweetness, and I'd rather adjust now than after pouring.
I pour the smoothie straight into my favorite glass and drink it right away while it's cold and thick. If I want it even thicker, I'll toss in a few ice cubes before this final blend.