Mix the wet ingredients

• Whisk the melted butter with the brown sugar and granulated sugar until smooth.
• Beat in the egg and vanilla extract until glossy.

Add the dry ingredients

• Add the flour and baking powder and fold until just combined.
• Fold in the chocolate chips, crushed graham cookies, Hershey's chocolate pieces and marshmallows.

Shape the cookies

• Scoop the dough into balls and place them on a lined baking tray, spacing them apart.

Bake

• Bake at 350 °F (180 °C) until the edges are golden.
• Let the cookies cool on the tray for a few minutes before serving.