Marble Banana Bread with Caramel Glaze

Ingredients:

For the Banana Bread:

2-3 ripe bananas, mashed
1/2 cup unsalted butter, melted
3/4 cup sugar
2 large eggs
1 teaspoon vanilla extract
1 1/2 cups all-purpose flour
1 teaspoon baking soda
1/4 teaspoon salt
1/4 cup cocoa powder
2 tablespoons milk
For the Caramel Glaze:

1/2 cup brown sugar
1/4 cup heavy cream
1/4 cup unsalted butter
1 teaspoon vanilla extract
A pinch of salt
Optional: chopped nuts or toffee bits for topping