Preheat oven to 350F. Line an 8-inch square pan with aluminum foil leaving overhang and spray with cooking spray, or grease and flour the pan; set aside.

In a large microwave-safe bowl, combine butter and chopped chocolate. Heat on high power to melt, about 2 minutes. Stir after 1 minute and then in 15-second increments until melted and smooth.

Allow the chocolate mixture to cool slightly. Add the eggs, granulated sugar, vanilla extract, optional coffee, and optional espresso granules. Whisk vigorously to combine.

Add the flour and salt. Stir until smooth and combined, being careful not to overmix.

Pour the brownie batter into the prepared pan and smooth the top with a spatula.

In a medium bowl, combine pumpkin puree, egg yolk, brown sugar, pumpkin pie spice, and vanilla extract. Mix well.

Dollop the pumpkin mixture over the brownie batter and spread it evenly.

Sprinkle the chocolate chips evenly over the pumpkin layer.

Bake for 35 to 40 minutes, or until the brownies are set. A toothpick inserted into the brownie layer should come out mostly clean (it's okay if it hits melted chocolate or a bit of gooey pumpkin).

Let the brownies cool completely on a wire rack for at least 2 hours before slicing.