4 ounces cream cheese, softened to room temperature
½ cups powdered sugar
1 teaspoon vanilla extract
Milk, as needed, for thinning
Preheat oven to 400°F. Line a muffin pan with baking cup liners and set aside.
First, make the muffin base. Add the flour, baking powder, baking soda, pumpkin pie spice, and salt to a large bowl and whisk until evenly distributed. In a separate medium-sized bowl, whisk together the melted butter, both sugars, eggs, pumpkin puree, and greek yogurt. Pour the wet mixture into the dry mixture and gently stir just until no large streaks of flour remain. Set aside.
Then, make the crumble. Whisk together the flour, both sugars, and the pumpkin pie spice in a medium-sized bowl. Pour in the melted butter, a bit at a time, and stir until pea-sized crumbs form.
Fill the lined muffin pan with the muffin batter to the top of each baking cup. Top generously with the crumb topping, gently pressing it down so the crumbs stick in the batter.
Bake for 10 minutes at 400°F, then reduce the temperature to 350°F and continue to bake until a toothpick inserted into the center of the muffins comes out clean, about 15 more minutes.
Keep the muffins in the pan to cool as you make the cream cheese glaze.
In a medium-sized bowl, whisk together the cream cheese and powdered sugar until well-combined. Whisk in the vanilla extract and thin with milk, as needed.