Spread the flour on a baking sheet and bake for 5 minutes to heat-treat.
Add the butter to a microwave-safe bowl, then melt. Pour the butter into a large bowl and whisk in half of the chocolate chunks until smooth.
Stir in the sugars, then the vanilla.
Measure the cocoa powder and salt into a sieve. Add the flour, then sift the dry ingredients into the wet ingredients. Stir until the batter is thick.
Pour in the milk a couple of tablespoons at a time, then mix the batter with a spatula or wooden spoon.
Fold in the remaining chocolate chunks. Add your favorite mix-ins if desired.
We like the batter at room temperature with berries as a dip or with ice cream for the ultimate treat!