Grind gingersnaps finely; add sugar and mix well. Add butter and mix well. Then press into bottom of 9-inch springform pan. Refrigerate until ready to use. Position rack in middle of oven. Then preheat oven to 350 degrees F.
Blend all ingredients until completely smooth. Pour filling into pan. Bake until edges of cake begin to pull away from sides of pan and cake begins to brown, almost 55 minutes.
Blend items for topping well. Without removing cake from oven, pour evenly over cake, starting at edges, spread if necessary. Bake 10 minutes. Remove and cool on rack. Refrigerate for 12 hours.
Let stand at room temperature for 30 minutes before serving.