Preheat the oven to 350°F.
1) To make the crust: Stir together the cracker crumbs, sugar, and melted butter.
2) Press the crumbs into a 9" pie pan that's at least 1 1/2" deep.
3) Bake the crust for 7 to 9 minutes, till it's barely beginning to color. Remove it from the oven.
4) To make the filling: Mix the sugar and ClearJel.
5) Blend into the softened cream cheese until smooth.
6) Add the vanilla, then the eggs, stirring till blended.
7) Pour the batter into the prepared crust.
8) Dollop the jam over the batter.
9) Use a small spoon to turn and swirl the jam into the batter.
10) Bake the cheesecake for about 40 to 45 minutes; the center will read 160°F on an instant-read thermometer, and will still seem soft and "jiggly."
11) Remove from the oven, and cool to room temperature, then refrigerate.
12) Serve topped with fresh raspberries and whipped cream, if desired.