Cinnamon and Chocolate Banana Bread

Name: Cinnamon and Chocolate Banana Bread
Ingredients: 1 1/4 cups unbleached all-purpose flour; 1 teaspoon baking soda; 1/2 teaspoon fine salt; 1/2 teaspoon pure vanilla extract; 2 large eggs, at room temperature; 1 cup sugar; 8 tablespoons (1 stick) unsalted butter, at room temperature; 3 very ripe bananas, peeled and mashed with a fork (about 1 cup); 1/2 cup toasted walnut pieces; 1 disk Mexican chocolate, chopped into small pieces; 3/4 cup unbleached all-purpose flour; 1/2 cup packed brown sugar; 1 tablespoon ground cinnamon; 8 tablespoons (1 stick) unsalted butter