Preheat the oven to 350°F (175°C).
In a large bowl, mix the dry ingredients: whole wheat flour, cocoa powder, baking soda, and salt.
In another bowl, whisk together the wet ingredients: honey (or maple syrup), Greek yogurt, eggs, and vanilla extract.
Pour the wet mixture into the dry ingredients and stir until just combined. Do not overmix.
Fold in the dark chocolate chips if using.
Pour the batter into a greased loaf pan and spread it evenly.
Bake for 45-50 minutes, or until a toothpick inserted in the center comes out clean.
Allow the bread to cool in the pan for 10 minutes before transferring to a wire rack.
Slice and enjoy your healthy chocolate bread!