S'mores Oatmeal Bars - Shared Appetite

Ingredients

• 1/2 cup unsalted butter, softened
• 1/2 cup granulated sugar
• 3/4 cup light brown sugar
• 1 egg
• 1 teaspoon vanilla extract
• 1 1/2 cups Bob's Red Mill Old Fashioned Rolled Oats
• 1 cup all-purpose flour
• 1/2 teaspoon baking soda
• 1/2 teaspoon Kosher salt
• 2 1/2 cups mini marshmallows, divided
• 2 cups chocolate chips, divided