Begin with the tangzhong. In a small pot, mash up a small banana with 23 grams of bread flour, then pour in 120 grams of water.
Cook over medium heat, stirring constantly, until the mixture thickens into a paste that looks almost gluey, around 6-7 minutes. If you have a thermometer it should read between 170-190°F. Cool this to room temperature before using.
Make the dough. In the bowl of a stand mixer, add 8 grams of active dry yeast, 45 grams of sugar, 120 grams of milk (between 100-110°F), 28 grams of melted butter and whisk.
Mash up one large banana very well. Whisk that into the wet ingredients along with 1 teaspoon vanilla bean paste and the tangzhong.
Add 430 grams of bread flour and 5 grams of salt. Use the hook attachment and mix on medium speed for 15-18 minutes, or until the dough goes from slack to pulling away from the sides of the bowl. It will be stretchy and tacky. You should be able to dampen your hand and stretch the dough up to 18 inches without it breaking to know that it's ready.
Use a damp hand to gently lift and place the dough so that it's a smooth ball, then cover and let it rise in a warm place for 60-90 minutes, or until doubled in size.
Make the filling. In a medium bowl, mix together 200 grams of brown sugar, 16 grams of cinnamon 18 grams of flour and 1/2 teaspoon kosher salt.
Quarter a banana lengthwise, then cut crosswise so you get a bunch of pea-sized banana pieces. Toss these in the sugar mixture so they are fully coated.
When the dough is done proofing, move it to a lightly floured work surface and roll it out into a 20-inch by 15-inch rectangle.
Spread 57 grams of softened butter evenly across the dough, then scatter the filling all over. Roll the dough up the 20-inch side, making a 15-inch long log.
This dough is soft, so you should use floss or a rubber band to cut the rolls (a knife will be a bit messy!). Trim the ends and cut the roll in 15 1-inch buns.
Use a bench scraper to transfer these rolls to a parchment-lined 9 by 13-inch baking slab. You will have five rows of three.
Cover the rolls and let them proof for another hour, or until they have increased around a third in size and look puffy.
Position a rack in the center of the oven and preheat to 375°F convection, 400°F standard.
Bake the rolls for 25-28 minutes or until they are golden.
While they are baking, make the banana caramel. Either mash 1 banana very well and stir it in with 120 grams of maple syrup, or blend them together in a blender.
Pour the mixture in a small pot and bring it to a boil. Let this boil for 60 seconds, then stir in a tablespoon of butter and 1/2 teaspoon salt. Let this get to rolling boil for another 60 seconds. When it smells very banana-y (or if you have a thermometer, when it's between 200°F-220°F) turn off the heat.
When the rolls are out of the oven, let them cool for a few minutes before glazing the top of the rolls with the banana caramel. Then cut, slice and eat as you like!