Preheat the oven to 350˚F. Line a 9 inch square pan with parchment paper. Set aside.
In a food processor, mix together the chia seeds, stevia, baking soda and salt. Set aside.
In a large saucepan, melt the butter and chocolate chips until smooth. Set aside to cool slightly.
Whisk in the eggs, then the coffee. Add in the chia seed mixture, and mix to combine. Fold in the chocolate chunks.
Pour the batter into the prepared pan and bake in the preheated oven for 15 minutes.
Remove and allow to cool in the pan completely.
Cut into 16 squares. Store in an airtight container.