Place squash in steamer basket set over 2 cups of boiling water and steam for 15 minutes, or until fork tender.

Drain and transfer to food processor or blender. Purée until smooth and creamy.

Measure out 1 cup and let it cool completely before using.

Preheat oven to 350 degrees F. Line 9-in. square pan with parchment paper, leaving some overhang for easy removal.

In large mixing bowl, whisk together cooled butternut squash purée, melted coconut oil, brown sugar, eggs and vanilla until smooth.

In medium bowl, whisk together flour, cacao powder, baking powder, salt and instant coffee (if using).

Add dry ingredients to wet mixture and stir gently until just combined.

Fold in 1/2 cup chocolate chips.

Spread batter evenly into prepared pan and sprinkle remaining 1/4 cup chocolate chips on top.

Bake for 22–25 minutes, or until edges are set and toothpick comes out with moist crumbs.

Cool in pan for 15 minutes. Slice once fully cooled.