Melt 1 stick butter in microwave. Crush cereal and 1/2 cup walnuts in small food grinder/processor. Place ingredients in bowl and add 1/2 cup sugar. Mix well. Pat into bottom and sides of springform pan.
Beat cream cheese with mixer until light. Add 1/3 cup sugar and beat again. add 1 cup brown sugar, add eggs one at a time and beat after each addition. Add canned pumpkin, pumpkin spice, heavy cream and corn starch. Mix well.
3Pour into springform pan and bake at 325 degrees for 1 hour 35 minutes or until firm around edges and still soft in the middle. Cake will continue to cook.
Combine 1 stick butter and 1 cup brown sugar. Add 1 cup walnuts. Mixture will be crumbly. Sprinkle over cake and refrigerate overnight.