Preheat oven to 180°C/350°F and lightly spray two 5-or 6-inch springform pans.
Mix the cookie batter wet and dry ingredients separately, then combine.
Mix the brownie batter wet and dry ingredients separately, then combine. Do not overmix.
Divide the brownie batter evenly between both pans.
Dollop the cookie batter over the brownie batter, gently spread, and add choc chips.
Bake 28-38 min (6-inch) or 32-42 min (5-inch), until the edges are set and the centers are slightly soft.
Cool in the pans for 30 minutes.
