In a large bowl, beat butter and sugar with an electric mixer until creamy. Add eggs and vanilla; beat until combined.

In a small bowl, combine flour, graham cracker crumbs, baking powder, and salt. Add to butter mixture, and beat until combined.

Turn the baking pan upside down and place a piece of waxed paper on top. Press half of the dough onto the waxed paper, using the bottom of the pan as a guide for the size. Set aside. Turn pan back over.

Press the other half of the dough evenly in the bottom of the pan. Spread marshmallow cream over the dough, but don’t go all the way to the edge. Lay the chocolate bars on top of the marshmallow creme, breaking apart as needed to create an even layer of chocolate. Take the preformed dough that you set aside earlier and invert onto the top of the chocolate and peel away the waxed paper. Spread gently to the edges if needed.

Bake for 25-30 minutes (mine was 27). Cool completely before cutting into squares.