Step 1

Preparation : Line a 9x13 baking pan with parchment paper or foil. Sift the sugar cookie mix, measure out 1 cup first, and then sift it. * It's easiest to line the pan with something that way you can lift out the fudge by the overhang and cut it evenly.

Step 2

Add the sliced butter into a medium sized saucepan, over low heat, and let it melt completely.

Step 3

Keeping it on low heat add the sifted sugar cookie mix, while whisking or stirring constantly, until completely blended with the melted butter.

Step 4

Turn the heat to medium, and add the evaporated milk and continue stirring or whisking until heated through.

Step 5

Add the granulated sugar, leaving the heat at medium, and continue cooking while stirring frequently until it reaches a rolling boil. This takes about 5-7 minutes.* If using a candy thermometer it should read 234° F. * A rolling boil is a vigorous, bubbling boil with a sort of churning and active motion. * Don't overcook. Once it reaches a rolling boil, that's good and you can continue on.

Step 6

Add the bag of white chocolate chips and stir until the chocolate chips have melted. Add the jar of marshmallow fluff and vanilla extract and continue to stir until all the ingredients are melted and blended together.

Step 7

Pour the fudge into the prepared pan and immediately top with the sprinkles. Allow the fudge to cool, on the counter at room temperature, for 15 minutes.

Step 8

Cover the pan with a lid or plastic wrap and let it refrigerate for at least 2 hours, or up to overnight. Lift the fudge out by the overhang and cut into small, bite-sized squares.