A perfect Fall dessert and a delicious alternative to pumpkin pie. These bars have a crispy cookie crust, delicious pumpkin filling, and toasted marshmallow topping.
Grease a 9 inch square pan and one side of a square piece of foil, to be used to cover the crust before baking. You may use an 8 inch square pan too, but may need to bake the filling a few minutes longer.
Place oven rack in middle position and preheat the oven too 400 degrees F
Add the flour, confectioners sugar, and salt to a food processor and pulse 2-3 times to blend.
Add the butter pieces and pulse 3-4 times.
Add the egg yolk and process in long pulses, about 10 seconds each, until dough forms some clumps.
Add the dough to the greased pan, spreading it evenly and pressing it down compactly and in an even layer. Prick all over gently with a fork. Cover with the foil, greased side down. Add dried beans or pie weights to top of foil.
Leave oven set to 400 degrees and place crust on a wire rack to rest while making the pumpkin filling.
Wipe crumbs from food processor bowl (no need to wash). Place all filling ingredients in bowl and process for about one minute, until smooth.
Pour filling into crust and bake for 10 minutes at 400 degrees, then lower oven to 325 degrees and bake for another 25-30 minutes, until filling is set and doesn't jiggle.
Place on wire rack to cool until barely warm
Stir corn syrup, water, and sugar in medium saucepan over medium-high heat until sugar dissolves. Place a candy thermometer into mixture. Continue boiling syrup without stirring until temperature reaches 238 degrees. It will take around 12-15 minutes.
Meanwhile, in a heavy duty mixer bowl with a whisk attachment, add egg whites, cream of tartar, and vanilla.
Once thermometer reaches 230 degrees, beat egg whites at medium speed until soft peaks form.
Once thermometer reaches 238 degrees, carefully pour hot syrup into bowl with egg whites while beating. Beat until topping is thick and glossy, about 2 minutes.
To toast marshmallow, turn oven to Broil setting.
Place in oven for about 30-45 seconds watching closely the whole time. Do not walk away as marshmallow topping can go from light brown to burned in just a few seconds.
You will need about 30 regular size marshmallows or 2 1/2 cups mini marshmallows. If using regular size ones, cut them in half and place them cut side down on pumpkin filling. Broil as described above in steps 5 & 7
Marshmallow topping may be made a day ahead and stored at room temperature