Preheat the oven to 180C/350F. Grease an 8 x 8-inch pan and set aside.
In a small saucepan or in a microwave-safe bowl, add your chopped chocolate. Melt your chocolate. Remove from the heat and add in your sugar and yogurt, and whisk until combined.
Add the flour, cocoa powder, and baking soda, and mix until just combined. Add your milk and mix well, until fully incorporated. Fold through your chopped Oreo cookies, reserving a few to top the brownies with.
Transfer the brownie batter into the lined pan and top with extra Oreos. Bake for 25-30 minutes, or until a toothpick comes out 'just' clean.
Remove from the oven and let cool completely, before slicing.
* You can also use homemade Oreos.TO STORE: Brownies can be stored in an airtight container at room temperature for up to 5 days. If you'd like them to keep longer, store in the refrigerator. TO FREEZE: Place leftover brownies in a ziplock bag and store in the freezer for up to 6 months.