While the dough is resting, prepare your bundt pan by greasing it with a bit of the stick of butter. If using a 9-inch springform pan, line the bottom with parchment paper, and then grease the bottom of and sides of the pan with the butter. Also grease the ramkein or jar for the middle and place it in the center of the pan. Melt the remaining butter stick in a medium bowl in the microwave. To the melted butter add mashed banana, brown sugar, and cinnamon and stir until well combined.
On a lightly floured surface, roll out the dough to about 12 x 18-inches. Spread ⅔ of the filling onto the surface. Add half the chocolate chips and the entire sliced banana in an even layer.
Fold the top and bottom edges of the dough into the center along the longest side. Now you have a long envelope of dough that is 18-inches long x 6-inches wide. Pinch the left and right ends together to seal the two edges. Then fold this envelope of dough in half again along the long edge. Cut 1-inch pieces along the length so you end up with 18 strips. This doesn’t have to be perfect and it will be a bit messy.
Place 9 strips, bunched and twisted, in messy bundles around the circumference of the bundt or springform pan. Add half the remaining filling and half the remaining chocolate chips evenly on top. Add the remaining 9 pieces on top of the first layer in the same fashion. Add remaining filling and chocolate chips on top as well as any filling that may have spilled onto the counter.