Caramel-banana upside-down pie

Ingredients:

3/4 cup brown sugar
3 tablespoons butter, cut into pieces
about 3 bananas, sliced into "coins"
1/2 cup chopped walnuts or pecans (optional)
1.5 cups flour
3/4 cup granulated sugar
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1/4 teaspoon cinnamon
1 cup banana puree (mash bananas with a fork)
2 large eggs
1/3 cup vegetable oil
1/3 cup buttermilk or sour milk
1 teaspoon vanilla extract

Caramel glaze:
2 tablespoons butter
2 tablespoons brown sugar
2 tablespoons heavy cream

Preparation:

Preheat the oven to 160 degrees. Grease a rectangular loaf pan with butter.
Evenly spread the brown sugar on the bottom of the pan. If using nuts, sprinkle them evenly over the butter. Place the butter evenly and put the pan in the oven for 8 minutes. Then mix everything until smooth at the bottom of the pan. Top with banana "coins".

Mix all the dry ingredients. Add the remaining ingredients and beat until smooth (don’t overmix).
Pour the batter over the bananas and place in the oven for an hour. Cool the cake for about 20 minutes before removing from the pan.

For the glaze, place all the ingredients in a small saucepan (can be done in the microwave) and heat. Bring to a boil and let simmer for about 2 minutes, stirring until smooth. Remove from heat and let sit for a minute, then pour the caramel over the cake.