Think I found it.

Yield:24 squares (one 9-by-13-inch pan)

¾cup/170 grams unsalted butter (1½ sticks)
Nonstick cooking spray or neutral oil
1¾cups/385 grams packed light brown sugar
¾cup/170 grams canned pumpkin purée (not pumpkin pie filling)
2teaspoons vanilla extract
2½cups/320 grams all-purpose flour
2teaspoons ground cinnamon
1teaspoon baking powder
1teaspoon baking soda
1teaspoon kosher salt (such as Diamond Crystal)
1teaspoon ground ginger
¼teaspoon ground cloves
¼teaspoon ground nutmeg
1½cups/9 ounces bittersweet or semisweet chocolate chips

Step 1

In a small (preferably light-colored) saucepan, melt the butter over medium heat. Continue cooking, stirring constantly to prevent the milk solids from burning, until the butter foams, darkens into a light amber color and becomes fragrant and nutty, about 3 to 4 minutes more. (Watch closely to make sure the butter doesn't burn.) Immediately pour the butter along with any of the browned milk solids into a large heatproof mixing bowl. Let cool for 20 minutes until warm but no longer hot.

Step 2

While the butter cools, heat the oven to 325 degrees. Grease a 9-by-13-inch metal or glass baking pan with cooking spray or oil and line with a strip of parchment paper that hangs over the two long sides to create a sling.

Step 3

Add the brown sugar, pumpkin purée and vanilla extract to the cooled butter and whisk until smooth and glossy. Add the flour, cinnamon, baking powder, baking soda, salt, ginger, cloves and nutmeg and stir with a spatula just until a soft dough forms with no pockets of unincorporated flour. (Try not to overmix.) Add 1¼ cups/216 grams of the chocolate chips and stir to evenly distribute throughout the dough.

Step 4

Transfer the dough to the prepared baking pan and press into an even layer using a spatula or clean hands coated with nonstick spray or oil. Sprinkle the top with the remaining chocolate chips, pressing them in so they stick. Bake until the bars are puffed, the top is lightly browned and a skewer or knife inserted into the center comes out clean with just a few moist crumbs attached or with smudges of melted chocolate, 30 to 45 minutes.

Step 5

Let the bars cool in the pan on a wire rack for at least 1 hour. Using the parchment paper, lift the bars out of the pan and cut into 24 squares. The cookie bars will keep in an airtight container at room temperature for up to 5 days.