Preheat the oven to 350 degrees and line a 9x9 inch baking pan with parchment paper or foil.

In a heavy saucepan over low heat, melt the butter and 1 cup chocolate chips; stir in the brewed coffee or instant espresso until smooth. Remove from the heat and set aside. Once the chocolate has cooled, stir in the sugar and whisk in the eggs, one at a time; stir in the vanilla. Then add the flour, cocoa powder, baking powder, and salt.

In a separate bowl, combine the vegetable oil, pumpkin puree and pumpkin pie spice.

Spread half of the chocolate batter in dollops into the bottom of the prepared 9x9 baking pan. Add dollops of the pumpkin puree. Drag a kitchen knife or small spatula gently through the layers, swirling the batter together to create a marbled appearance. Top with 1/4 to 1/2 cup of chocolate chips.

Bake in the preheated oven until the brownies begin to pull away from the side of the pan and a toothpick inserted into the center comes out mostly clean; about 40 to 45 minutes. Cool in the pan completely before cutting into 16 squares.