Brownie & Marshmallow Crunch Bars

Ingredients

• 4 ounces unsweetened chocolate
• 2/3 cup unsalted butter
• 1 1/4 cups semisweet chocolate chips, divided
• 1 1/3 cups all-purpose flour
• 1 tsp. baking powder
• 1/2 tsp. salt
• 4 large eggs, at room temperature
• 2 cups granulated sugar
• 2 tsp. vanilla extract
• 1 bag (10½ ounces) miniature marshmallows
• 1 1/2 cups milk chocolate chips
• 1 cup smooth peanut butter
• 1 tbsp. unsalted butter
• 1 1/2 cups crisp rice cereal