Defrost phyllo dough according to manufacturer's instructions. Place phyllo at room temperature for 2 hours. Unroll and cover with plastic wrap and a damp towel.
Preheat oven to 350℉
Brush pie pan generously with melted butter.
Take one sheet of phyllo and place on a surface - be sure to replace damp towel over remaining pieces. Brush lightly with melted butter.
Place another sheet of phyllo over top of sheet you just worked on. Brush lightly with melted butter.
Starting with the long end of phyllo, begin creating an accordion shape. To do this take about an inch of phyllo and gather it together using your fingers. Continue gathering until you reach the end of the dough. Note: create loose folds - space is needed between folds to insert banana slices.
Roll the phyllo into a spiral shape and place in the middle of your pie pan.
Take one sheet of phyllo and place on a surface. Brush lightly with melted butter. Add another sheet of phyllo over top of the sheet you just worked on. Brush lightly with melted butter. Fold accordion-style.
Gently lift the dough and wrap around spiral already in pan. Repeat this four more times, filling the pie pan with dough.
Chop bananas into ⅛ slices and insert between phyllo folds. Sprinkle top with chocolate chips.
Make custard by whisking together heavy cream, granulated sugar, eggs and cinnamon until well combined.
Pour custard evenly over top of pie.
Bake in preheated 350℉ oven for 30 - 35 minutes. The top will be golden brown.
Remove from oven and place on a wire rack for 20 minutes before serving.