Line an 8x8 inch square baking pan with parchment paper.

Place 1.25 cups of the pistachios in a food processor and pulse until they reach a fine, crumb-like consistency.

Add the cocoa powder and sea salt to the food processor and pulse briefly to combine.

Add the pitted dates and maple syrup to the processor and blend on high until the mixture forms a cohesive, sticky dough that pulls away from the sides.

Transfer the mixture to the prepared baking pan and press down firmly with a spatula or the bottom of a glass to create an even layer.

Finely chop the remaining 0.25 cups of pistachios and press them into the top of the brownie layer.

Refrigerate the pan for at least 60 minutes to allow the structure to firm before slicing into 12 bars.