Prep your pan and oven. Preheat oven to 350°F (175°C).
Line an 8x8-inch pan with parchment, leaving an overhang for easy lifting. Lightly spray with oil.
Combine dry ingredients. In a large bowl, whisk protein powder, almond flour, cocoa, sweetener, baking powder, salt, and espresso powder (if using) until no clumps remain.
Mix wet ingredients. In a separate bowl, whisk eggs, almond milk, Greek yogurt, melted coconut oil, and vanilla until smooth and glossy.
Stir in melted chocolate. Pour the melted dark chocolate into the wet mixture and whisk quickly to combine.
Bring it together. Add wet ingredients to the dry. Stir with a spatula until just combined.
The batter will be thick—closer to a scoopable consistency than pourable.
Fold in chips. Gently fold in the sugar-free chocolate chips, reserving a small handful for the top.
Spread and top. Scoop batter into the prepared pan and smooth the top. Scatter remaining chips evenly over the surface.
Bake. Bake for 18–22 minutes, until the edges are set and a toothpick inserted in the center comes out with a few moist crumbs. Do not overbake.
Cool completely. Let brownies cool in the pan on a rack for at least 30–45 minutes.
Lift out using parchment and slice into 9–12 squares.
Optional finishing touch. For extra gloss, warm 1 tablespoon almond milk with a few chocolate chips and drizzle over the cooled brownies.