Preheat oven to 182°C.
Grease an oven-proof cake pan or skillet.
Cream butter and sugars together for five minutes, until pale and fluffy. Scrape the bowl and add the eggs and vanilla extract and salt. Beat for five more minutes. Scrape the bowl and add the flour, cinnamon, and baking soda on top. Slowly stir to incorporate. When homogeneous, mix vigorously for 30 seconds to ensure homogeneity.
Stir in the chocolate chunks and press the dough into the skillet.
Bake for 45-50 minutes, until set and golden brown (careful not to overbake).
Slice as desired and serve with vanilla ice cream or chocolate ganache.