Preheat oven to 350 degrees. Line a 12-cup muffin pan with baking liners.
In a small bowl, add all the crumb ingredients except the butter. Mix until well combined. Add butter and mix in with a fork until it has a crumble appearance. Set aside.
In a medium-size bowl, add flour, allspice, 2 teaspoons cinnamon, baking powder, baking soda and salt. Whisk until well incorporated.
In a stand mixer or mixing bowl, add butter, oil, white and brown sugar. Mix on medium until well combined, or about 2 minutes.
Mix in butter until well incorporated. Do the same with the pumpkin puree. Slowly whisk in the dry ingredients until well incorporated. Fold in chocolate chips.
Layer each muffin cup 2/3 of the way with pumpkin batter. Add about 1 tablespoon of the crumb topping. Bake 18-20 minutes or until it springs back when touched. Let cool.
In a microwave-safe bowl, add chocolate chips and milk. Melt at 50% power for 30 seconds. Stir and repeat until completely melted. If not thin enough to drizzle add a few drops of milk to thin it out. Drizzle over the muffins and serve.