Mix espresso and syrup in a shallow dish; set aside.
Mix sugar and pumpkin pie spice together. Reserve ½ teaspoon of the sugar mixture and set aside.
In a large bowl, whisk remaining spiced sugar with mascarpone and pumpkin puree until well blended and creamy.
Reserve 1 lady finger. Quickly dip remaining lady fingers, one at a time, into the espresso mixture, allowing excess espresso to drip back into the dish. Place a single layer of dipped lady fingers on the bottom of a 9x5-inch loaf pan.
Spread ⅓rd of the pumpkin filling over the top in an even layer.
Top with another layer of dipped lady fingers and filling. Repeat one more time smoothing the top.
Using a rolling pin, crush reserved lady finger and ½ teaspoon of spiced sugar in a plastic bag. Sprinkle crumbs over the top of the tiramisu. Cover with plastic wrap and refrigerate for at least 8 hours or as long as overnight.
Garnish as desired.