Preheat your oven to 350°F (175°C) and spray a tart pan with non-stick spray.

In a large mixing bowl, combine very soft butter, granulated sugar, pure vanilla extract, and salt. Beat until creamy, about 2-3 minutes.

Add all-purpose flour and graham cracker crumbs to the mixture, blend until large crumbles form, about 1-2 minutes.

Press about one-third of the dough into the bottom of your prepared tart pan evenly and compactly.

Bake for 10-12 minutes until edges are lightly golden, let cool for 15 minutes.

Spread marshmallow creme over the cooled crust, leaving a small border around the edges.

Sprinkle half of the chocolate chips over the marshmallow and gently press them down.

Crumble remaining dough over the top, covering as much of the surface as possible.

Bake for 25-35 minutes until the top is golden brown and slightly puffed.

Allow cooling in the pan for about 1 hour, then top with Hershey bar pieces while still warm.