Preheat oven to 325°F. Line a baking sheet with parchment paper and grease the parchment with butter or cooking spray.
In a small bowl, whisk together almond flour, baking powder, and salt. Break up any lumps.
In a large mixing bowl, beat room temperature egg whites with an electric mixer until frothy (like soap bubbles), but not stiff peaks.
With mixer running on medium speed, slowly add erythritol and let it dissolve. The mixture will thicken slightly.
Add cocoa powder and instant coffee to the egg white mixture. Mix until smooth and dark chocolate colored.
With mixer still running, slowly pour in melted butter in a thin stream. Add heavy cream and vanilla extract. Mix until smooth and glossy.
Add dry ingredients and mix just until combined. Don't overmix.
Pour batter onto prepared pan. Spread into a 12x8 inch rectangle using an offset spatula, keeping thickness even. Scatter chocolate chips on top and press down gently.
Bake for 18 minutes. Remove from oven and turn off oven completely. Let bark sit on counter for 15 minutes.
Using a sharp knife or pizza cutter, score the bark into 2-inch squares (about 24 pieces total). Cut all the way through but don't separate pieces.
Return scored bark to the warm oven for 5-10 minutes to crisp up. If oven cooled too much, reheat to 175°F first.
Remove from oven and let cool completely on the counter. Once cool, break along score lines. Each piece should snap cleanly.