Warm milk in the microwave until it hits 100–110°F (about 60–90 seconds total).
In a large bowl, whisk warm milk and yeast. Let sit for 5–10 minutes until foamy.
Add in brown sugar, melted butter, eggs, mashed bananas, and vanilla. Mix well.
Add 4 cups of flour and salt. Begin mixing, then slowly add up to 3/4 cup more flour until the dough pulls away from the sides and is only slightly sticky.
Knead by hand or mixer for 8–10 minutes. Form into a ball, place in a greased bowl, cover with a towel, and let rise in a warm area for 60–90 minutes or until doubled in size.