To Make Cereal Crust:

Stir crushed cereal, granulated sugar and melted unsalted butter together in a medium size bowl until evenly combined. Firmly press into the bottom and sides of a lightly greased 8-inch or 9-inch springform pan.  (Using a 1/4 cup measuring cup to help press crust into the pan is helpful.)   Chill in the freezer while preparing the cheesecake filling.

To Make Cheesecake Filling:

Using either a standing mixer or hand-held mixer, beat cold heavy cream and 2 tbsp. powdered sugar until stiff peaks form, about 2 to 3 minutes on high speed.

In a separate large bowl, beat cream cheese, marshmallow fluff, granulated sugar, and powdered sugar until smooth.  Add sour cream, vanilla, and almond extract.  Continue beating until smooth and well-incorporated.  There shouldn’t be any lumps. Gently fold stiff whipped cream into the cream cheese mixture until evenly combined.  If not coloring the filling, pour directly into chilled crust and refrigerate. 

If coloring the filling or using the rainbow design, divide filling evenly into 6 bowls to color into red, orange, yellow, green, blue and purple colors. Gently stir colors into filling.  Pipe each color into concentric circles inside the crust.  Repeat until filling is completely piped into crust.  Smooth top with an off-set spatula.  

Pour into prepared cereal crust.  Use a knife to swirl the colors together, if desired.  Cover pan with either aluminum foil or plastic wrap.  Refrigerate cheesecake for 6 to 8 hours, or up to 2 days, before serving.*

To Make Whipped Cream Garnish:

Using a standing or hand-held mixer, whip heavy cream and powdered sugar until stiff peaks form.  Pipe onto cheesecake in decorative design (if desired).  Garnish cheesecake with additional marshmallows and sprinkles.