1. Preheat the oven to 350 degrees F. Line an 8 x 4 x 2½-inch loaf pan with two pieces of parchment paper, overlapping the pieces and allowing the paper to drape a bit over the sides of the pan.

2. Put the water and chia seeds in a small bowl and stir to combine. Let rest for 10 minutes, until the mixture thickens into a gel.

3. Put the chocolate chips, coffee, and butter in a small glass or ceramic bowl and microwave in intervals of 10 to 15 seconds, stirring between each interval, until the chips are melted. Alternatively, put the chocolate chips, coffee, and butter in a double boiler over medium-low heat until the chips are melted. Transfer to a large bowl.

4. Add the sugar, cacao powder, and vanilla extract and stir until the sugar dissolves. Add the flour, salt, and baking soda and stir to form a thick batter. Gently stir in the optional chopped walnuts (or sprinkle them over the batter, as described in the next step).

5. Transfer to the lined loaf pan and press the batter evenly into the pan using a silicone spatula. If the optional walnuts weren’t added to the batter, you can sprinkle them over the top of the batter now. Bake for 20 to 22 minutes, or until the top feels dry. Let cool for 15 minutes in the pan, then lift out of the pan using the parchment paper and transfer to a rack to cool completely. Cut into 6 pieces with a sharp knife.

Per brownie: 264 calories, 4 g protein, 11 g fat (4 g sat), 40 g carbs, 126 mg sodium, 0 mg calcium, 3 g fiber

Save for Later: Stored in an airtight container, the extra brownies will keep for 5 days at room temperature or 2 months in the freezer.