Blondies Meet Banana Bread in This Rich, Chewy Dessert

Ingredients (14)

• Cooking spray
• 2 just-ripe bananas (about 11 ounces; 312 g), unpeeled
• 12 tablespoons (6 ounces; 170 g) unsalted butter, softened 
• 213 g packed light brown sugar (7 1/2 ounces; 1 cup)
• 99 g granulated sugar (3 1/2 ounces; 1/2 cup)
• 1 large egg
• 2 teaspoons (10 ml) vanilla extract
• 255 g all-purpose flour (9 ounces; 2 cups)
• 1 teaspoon Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight
• 1 teaspoon ground cinnamon
• 1/4 teaspoon ground clove
• 1/4 teaspoon ground nutmeg
• 5 ounces (142 g) bittersweet chocolate, 60% cacao, chopped (about 1 cup), divided
• 2 teaspoons flaky sea salt (such as Maldon), optional