1. **Prepare the Dates:** If your dates are dry or stiff, soak them in a bowl of hot water for 10 minutes to soften. Drain them thoroughly before using.

2. **Process the Dry Ingredients:** In a food processor, pulse the walnuts (or almonds) and cocoa powder until the nuts are finely ground. (Be careful not to over-process into nut butter).

3. **Make the Dough:** Add the pitted dates, ¼ cup peanut butter, vanilla extract, and salt to the food processor. Pulse until a sticky, unified dough forms. It should hold together when pinched between your fingers. If it’s too crumbly, add 1 tablespoon of water and pulse again.

4. **Press into Pan:** Line an 8×8 inch square baking dish with parchment paper, leaving some overhang for easy removal. Dump the dough into the pan and press it down firmly into an even layer using the back of a spatula or your hands.

5. **Melt the Chocolate:** In a small microwave-safe bowl, combine the chocolate chips and coconut oil. Microwave in 30-second intervals, stirring in between, until completely melted and smooth.

6. **Add the Swirl:** Pour the melted chocolate over the brownie base and spread it to the edges. Dollop the remaining 2 tablespoons of peanut butter randomly over the wet chocolate.

7. **Create the Marble Effect:** Use a toothpick or the tip of a knife to swirl the peanut butter into the chocolate, creating a marbled pattern.

8. **Chill:** Place the pan in the refrigerator for at least 1–2 hours (or freezer for 30 minutes) to allow the chocolate to set and the base to firm up.

9. **Serve:** Lift the brownies out of the pan using the parchment paper handles. Slice into 16 squares. Store leftovers in the fridge.