In a small saucepan, add butter and milk and heat, stirring constantly until butter is melted and milk is warm.
Remove from heat and let stand to cool until it's 110 degrees F. Pour into a large mixing bowl and add yeast. Mix well and let stand for 10 minutes for yeast to activate.
Stir in mashed banana, sugar and salt. Add 2-1/2 cups flour, half at a time, Mix until combined well.
Spoon dough onto a floured surface and knead a few times, adding a bit of additional flour until dough is mixed and non longer sticky. Rinse the mixing bowl and coat with nonstick cooking spray. Place dough in bowl and cover with plastic wrap. Place in a warm location and let dough rise to double in size, this will take about 1 hour.
Remove the dough from the bowl and place onto a floured surface. Using a rolling pin, dusted in flour, roll dough thinly, about 1/4" thick and around the size of 12×20 inches. Brush dough with melted butter (you won't use it all).
Mix together sugar and cinnamon and sprinkle on top of butter. Top with thinly sliced bananas.
Preheat oven to 350. Grease a 10" ovenproof skillet. Starting with the long edge roll the dough into a log. Use a serrated knife to cut into 2" cinnamon rolls. You should have about 10 rolls. Place into prepared pan. Brush with remaining melted butter. Cover with plastic wrap and let rolls rise while oven preheats, about 10-15 minutes.
Remove plastic wrap and bake for 25-30 minutes or until golden brown. Remove from oven and let stand until warm. Spread frosting on top and serve.