Preheat oven to 350 degrees Fahrenheit
Melt chocolate and butter/coconut oil together. Use high power for 1 minute in the microwave then stir until smooth.
Add Greek yogurt, vanilla, eggs, sugar, and salt. Mix or beat well.
Stir in cocoa powder and baking soda.
Grease or line an 8 x 8 cake pan with parchment paper. Spread batter evenly in the pan.
Bake for 35-40 minutes, until a toothpick comes out clean!
Serving Size 1