Mix the wet ingredients

• Whisk the melted butter with the white sugar and brown sugar.
• Add the egg, egg yolk and vanilla extract and mix until shiny.

Add the dry ingredients

• Combine the flour, baking powder and salt.
• Fold into the wet mixture with a spatula until just combined.

Fold in the s'mores mix-ins

• Stir in the chocolate chips, crushed graham crackers and marshmallows.

Bake

• Spread the cookie dough in a baking dish.
• Bake at 175 °C (350 °F) until the edges are set and the center is still soft.

Serve

• Let cool slightly and serve warm with a spoon.