When dough has risen, remove cover and, using your fist, punch the dough down and remove from the bowl. Roll out on a well-floured surface into a 16x24 inch rectangle and spread the remaining 2 tablespoons of melted butter almost out to the edges, but not quite.
Mix the brown sugar with the cinnamon and sprinkle evenly across the butter. Slice the bananas and layer evenly over the brown sugar mixture. Sprinkle chopped walnuts over the bananas.
Roll into a log, starting from one end to the other, lengthwise, so the log is 24 inches. Using a serrated knife, gently cut 2 inch slices with a sawing motion (try not to push too hard to pinch the dough), this will give you 12 cinnamon rolls. Quick tip: if you don’t want to measure 2 inches out for every roll, cut the log in half, then cut each piece in half again. You have 4 pieces now. Then cut each fourth into 3 pieces. Now you have twelve even slices.
Butter a 9x13 baking pan. If you want your cinnamon rolls in a round shape, place the cinnamon roll slices close together, but not touching, in the pan. I like mine to be squished together so that they become a rectangle. So I let them touch. Cover with plastic wrap and let rise until the dough is doubled, 1 -1½ hours.
When the rolls have 20 minutes left to rise, preheat the oven to 375°F. Bake for about 22-24 minutes, or until they are deep golden brown on top. If you like them more doughy, you can remove once they begin to get lightly golden brown on top.