Preheat the oven to 325 degrees and line the bottom of a 9x9 baking pan with parchment paper.
Melt the chocolate chips, butter, and olive oil in a small saucepan over medium heat, stirring often, until creamy. Set aside.
Whisk the cocoa powder, flour, protein powder, and salt in a medium bowl.
Whisk the eggs, brown sugar, granulated sugar, and vanilla extract in a large bowl. Add the melted chocolate and mix again.
Add the dry ingredients to the wet ingredients and mix with a rubber spatula until just combined. Fold the chopped chocolate bar into the batter.
Pour the batter into the pan and spread it evenly. Bake for 34 to 48 minutes until a toothpick inserted into the center comes out mostly clean.
Cool the brownies in the pan for at least an hour until the top is cracked and the brownies are set. Slice and enjoy.
Notes
Storage
Store the brownies at room temperature for up to 4 days in an airtight container.
Wrap individual brownies in plastic wrap and freeze them for up to 2 months in an airtight, freezer-safe container.
Bring to room temperature before serving.
Tips
Mix the batter until just combined to avoid tough brownies.
Stir the chocolate constantly while melting it to avoid scorching.
Leave an overhang on either side of the pan when you line it with parchment paper to make removing the brownies easier.
For baked goods, always bring cold ingredients to room temperature before mixing unless otherwise specified. It makes mixing easier and helps avoid overmixing.