Spray an 8-inch or 9-inch square pan with cooking spray and line with foil.

Combine graham cracker crumbs, butter, and sugar in a small bowl and stir until combined.

Press the graham cracker crumb mixture into the bottom of the prepared pan and press down firmly. (Hint: Use the bottom of a measuring cup to really pack it in.)

Refrigerate crust while preparing fudge.

Combine the sweetened condensed milk and pumpkin in a heavy bottomed pot. Cook over low heat for 10 minutes, stirring almost continuously.

Stir in the white chocolate chips. Continue cooking over low heat, stirring frequently, until the chocolate has melted.

Stir in the pumpkin pie spice and cook an additional five minutes, stirring frequently.

Pour into prepared pan and refrigerate for at least four hours before cutting into squares and serving.

If you want to add the chocolate drizzle, melt white chocolate chips and shortening together and drizzle over the top of the cut pieces of fudge.

Store leftovers in an airtight container in the fridge.