Beat eggs, sugar, yogurt, pumpkin and vanilla until well blended.
In a separate bowl, combine flour, pumpkin spice, baking powder, baking soda, and salt. Gradually add dry ingredients to pumpkin until well blended. Pour into prepared pan.
Bake for 25 to 30 minutes or until a toothpick inserted in the center comes out clean. Cool completely before making frosting.
In a large bowl, combine cream cheese, butter, vanilla, milk, and powdered sugar. Beat with an electric mixer until smooth and combined. If you need to add more milk, you can add it in very small amounts but remember you want the frosting to be thick so it will hold its shape.
Cut cooled bars into rectangles. I make one long cut down the pan the long way and then cut the other way until I have 18 bars.
Using a piping bag and a piping tip with a long, thin opening (I used one similar to a Wilton 104), pipe small dots for the eyes (you can also use a toothpick for this), and place eyes on top of frosting. Then, work back and forth with the frosting to create a mummy effect. It doesn’t have to be perfect!
Notes
If you prefer, simply make the pumpkin bars and frost them before cutting them into squares, if you don't want mummy bars.