S'mores Cookie Bars

Bahan-bahan (16 porsi)

• 1/2 cup (8 Tbsp; 113g) unsalted butter, softened to room temperature*
• 3/4 cup (150g) packed light or dark brown sugar
• 1 large egg, at room temperature
• 1 teaspoon pure vanilla extract
• 1 cup (125g) all-purpose flour (spooned & leveled)
• 1 cup (120g) graham cracker crumbs (about 8 full-sheet graham crackers)
• 1/2 teaspoon baking powder
• 1/4 teaspoon salt
• 1 cup (180g) semi-sweet chocolate chips
• 1 heaping cup marshmallow creme (store-bought “Fluff” or 1/2 recipe of homemade marshmallow creme)