Preheat oven to 350 degrees F. Spray a 9x13- inch baking dish with nonstick cooking spray; set aside.
In a large mixing bowl, melt chocolate chips for 1-2 minutes, stirring every 30 seconds, until melted.
Remove from microwave and mix in yogurt until completely smooth. Add Truvia, protein powder, flour, cocoa powder, baking soda and almond milk; mix until well combined.
Spread batter in prepared pan and bake for 25- 30 minutes, or until an inserted toothpick comes out clean. Remove from oven and let cool completely before serving.