To prepare browned butter, place 6 tablespoons (85g) butter into a sauce pan over medium high heat. Butter will melt and begin to foam. Using a whisk, stir constantly. Foam will subside, brown bits will form at the bottom and the butter will have a nutty smell. Remove from heat, pour into a heat proof bowl and cool for 15 minutes to room temperature. Transfer to the fridge to chill an addtional 20-30 minutes. Butter should be soft, but not cold in order to cream. If it has turned cold, bring to room temperature for 10 minutes. Alernatively, prepare browned butter the day before or use regular unsalted butter. Bring to room temperature before baking, along with all the other ingredients. Layer 2-3 paper towels in a small shallow bowl. Scoop slightly over ½ c pumpkin onto the paper towels. Allow the pumpkin to sit on the paper towels for about 15 minutes. After 15 minutes, gently squeeze the liquid released into the paper towels. Discard the liquid. Scoop ⅓ c (80g) "blotted" pumpkin into the bowl and set aside.
In a separate bowl, whisk together flour, finely crushed graham crackers, pumpkin spice, baking soda and powder and salt. Set aside.
In a mixing bowl, with paddle attachment, cream together the browned butter, sugars and tahini until light and fluffy (~4-5 minutes).
Add in the egg and blotted pumpkin one at a time, beating well after each. Add vanilla and beat again for about an additional minute.
On the lowest mixer setting or by hand using a silicone spatula or spoon, stir in dry ingredients to the wet ½ at a time. Mix until JUST combined. Fold in ⅓ c chocolate chips.Loosely cover the dough in plastic cling. Place dough in the fridge to chill for one hour. Preheat the oven for at least 30 minutes. Line a 8x8" (20cm) baking pan with parchment paper, leaving 1-2" of an overhang on two sides. This "sling" helps to remove the bars from the pan after cooling.
Roughly divide the chilled cookie dough into thirds. Reserve about ⅓ for topping. Evenly press ⅔ of the chilled dough along the bottom of the prepared baking pan.
Scoop even dollops of marshmallow creme along the chilled dough. A spoon dipped in hot water can help. Spread the marshmallow creme evenly along the bottom.
Top the marshmallow creme with roughly crushed pieces of graham crackers.
Top with ½ c of semi sweet chocolate chips (or hershey bar pieces for a more classic touch).
Top everything with the remaining ⅓ of the chilled dough. This will not completely cover the top of the bars. Instead, scoop dough into your hand. Press it into a flat disk and place around the pan. This is similar to topping a fruit cobbler with biscuit dough. This is done so the filling pushes through. Top with the remaining chocolate chips if desired. Bake in a 350F (177 C) oven for 25-32 minutes or until golden brown with set edges pulling slightly from the edge of the pan. At 25-28 minutes, the edges will be baked and the center will be slighlty underbaked. This is my prefered way. For more well baked bars, bake 28-32 minutes. Cool pan on a cooling rack for 45-60 minutes. Bars are cool enough to eat at 30 minutes, but they will not be firm enough to lift out of the pan until closer to an hour. Using the sling, remove bars from the pan, slice and enjoy!