Ingredients:

Chocolate Chip Cookie Base

• 50g butter, room temp.
• 25g castor sugar
• 25g brown sugar
• 28g yogurt, room temp.
• 1/2 tsp vanilla extract
• 70g plain flour
• 1/4 tsp baking soda
• 1/4 tsp salt
• 70g dark chocolate chips/chunks

Brownie mix:

• 42g butter
• 70g dark chocolate
• 100g castor sugar
• 80g yogurt, room temp.
• 1 1/2 tbsp milk, room temp.
• 62g plain flour
• 12g cocoa powder
• 1/4 tsp salt
• 1/2 tsp baking soda

Process:

Make the cookie base:

1. Preheat oven to 180°C. Grease and line an 8 x 6-inch baking pan (or an 8-inch circular pan) with baking parchment.
2. In a bowl, cream together butter and both sugars until pale and fluffy.
3. Add vanilla and yogurt, mix well.
4. Sift in the dry ingredients and combine.
5. Lastly, add the chocolate chips and fold it in.
6. Spread out cookie dough in the pan in an even layer.
7. Bake at 180°C for 12 minutes.
8. Leave to cool while you make the brownie mix.

Make the brownie mix and bake again: 

1. In a heatproof bowl, melt the butter and chocolate together. (Use a microwave oven or double boiler).
2. While the chocolate mixture cools a little, mix dry ingredients (except sugar) in a separate bowl and keep it aside.
3. Add sugar to the chocolate-butter mixture and whisk to combine.
4. Next, add yogurt and milk and mix well.
5. Sift in dry ingredients and whisk to combine.
6. Transfer brownie mix onto the baked cookie layer and spread evenly.
7. Bake in a 175°C oven for 25-30 minutes. The centre should be a little underdone as compared to the sides.
8. Leave to cool in the pan completely, then cut into pieces and serve.