Place all ingredients into a blender and blend until smooth. Tip: it helps if you soak your dates beforehand to make them easier to blend.
For the streusel topping:
Combine flour, cocoa powder, and brown sugar. Add melted butter and mix until crumbly.
For the muffins:
Preheat oven to 350ºF and lightly oil a muffin tray, or line it with 12 paper/silicone liners.
In a large bowl, combine flour, baking powder, salt, cinnamon, nutmeg, and ginger. Set aside.
In a medium sized bowl, whisk together the milk and sugar. Add the egg, butter, and vanilla. Stir in canned pumpkin and mix well until fully combined.
Pour wet ingredients into dry and stir gently until just combined. Do not overmix.
With a spoon, spoon batter into muffin tins until about 1/3 way full. Add 1 tsp. chocolate filling to each tin, and cover with more muffin batter until tins are about 2/3 full. Finish by sprinkling a generous amount of streusel topping onto each tin.
Bake muffins for 20 minutes, or until a toothpick inserted into the center comes out clean. When finished, allow to cool for about 5 minutes before removing them from the muffin tin and allowing to cool completely on a wire rack.