Preheat the oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until fluffy and light.

Add the eggs one at a time, mixing well after each addition. Then, fold in the vanilla extract.

Incorporate the flour, baking soda, salt, butterscotch chips, and white chocolate chips until a rich cookie dough forms.

Press half of the cookie dough into the prepared pan.

In another bowl, whip together the cream cheese, granulated sugar, egg, vanilla extract, and sour cream until smooth.

Spread the cheesecake mixture evenly over the cookie base.

Melt the butterscotch chips with heavy cream and salt over low heat. Drizzle this mixture over the cheesecake layer.

Spoon dollops of marshmallow fluff over the surface and create swirls.

Drop spoonfuls of the remaining cookie dough on top.

Prepare a crumb mixture using crushed vanilla wafers, chopped pecans, melted butter, and brown sugar, and sprinkle over the top.

Bake for 25-30 minutes until golden.

Once cooled, drizzle with additional butterscotch, mini marshmallows, and crushed wafers before serving.