Step 1

Preheat oven to 180°C/350°F (160°C fan forced).

Step 2

Spray a 20cm/8" square tin with oil and line with baking/parchment paper with overhang (Note 2).

Step 3

Place butter and chocolate chips in a heatproof bowl, microwave in 30 second bursts (takes me 1m 30 sec) until melted. Stir until smooth.

Step 4

Add sugar and vanilla, mix, then add eggs and mix well until smooth and molten.

Step 5

Add flour, cocoa and salt and stir until smooth. Stir in chopped chocolate, pour into pan.

Step 6

Bake 24 minutes for really gooey in the centre, 28 minutes for fudgey but still very moist (my favourie, shown in video & photos), 32 minutes for moist fudge-cake-like. (See in post for toothpick testphotos).

Step 7

If you didn't use the extra chocolate for stirring in, reduce cook time by 2 minutes.

Step 8

Rest for 10 minutes before lifting out of the pan. Allow to cool for at least 20 minutes before cutting. Store in an airtight container for 4 days (bet they don't last that long!) or freeze for 3 months.