If using frozen raspberries, remove them from the freezer before starting the recipe to allow them to thaw for a few minutes. Then, preheat the oven to 350°F (180°C) and grease a muffin pan or line it with paper muffin cups.
In a large bowl, mix the sugar, oil, yogurt, and vanilla. Add the flour, cacao powder, salt, baking powder, and baking soda using a spatula or wooden spoon, until you get a smooth batter.
Gently fold in the chocolate chips and raspberries.
Spoon the batter into the muffin cups and bake for 30 minutes if you're making 12 small muffins, or 35 minutes if you're making 9 larger muffins, until a toothpick comes out clean.
