Preheat your oven to 340°F and line a square baking tin with parchment paper.
Start by making the caramel: mix all the caramel ingredients together and set aside.
In a small saucepan, melt the butter over medium-low heat. Keep it on low to ensure even browning. Stir until the butter starts to foam, gives off a nutty aroma, and turns golden brown. Remove from heat.
Pour the browned butter over the dark chocolate, then stir in the sugars until dissolved.
Add the milk and yogurt, stirring until smooth.
Sift in the flour, baking soda, and cocoa powder, and mix until the batter is smooth and glossy.
Fold in the chocolate chunks.
Pour the batter into the prepared tin.
Swirl the caramel through the batter.
Bake for 25-30 minutes, or until almost fully set.
Allow to cool completely before slicing and enjoying!