Use your 9-inch springform pan. Pour the crumbs, sugar, and butter in the bottom of the pan. Mix with a fork until well blended. Press the crumb mixture with your fingers to form a bottom crust. It doesn't need to go up the sides, just on the bottom.
Bake the crust at 350 degrees for 8 minutes. Let cool while you blend the next items.
With your mixer, in a large bowl, blend the cream cheese, sour cream, sugar, flour, and one of the eggs until smooth. Then add each additional egg, one at a time, and blend each one in before adding the next one.
Pour half of the mixture on top of your cooled crust. Open the jar of jam and, by teaspoonful, gently lay the jam on top of the filling. As much as possible, you want the jam to rest on top of the filling so set the jam on top of the filling rather than plop it in. When all the jam is distributed over the top of the filling, use a knife to slightly spread it and break up any larger globs. This isn't very scientific, so don't be too picky. Just don't slide it around too much like some recipes suggest because you want a "ribbon" of jam to form as it bakes. You don't want it blended in.
Then pour the rest of the filling on top.
Bake at 350 degrees for 65 minutes. It will be slightly jiggly but not mushy. When it's done, turn off the oven and let the cheesecake sit in the oven 15 minutes more with the oven door ajar. Then take it out of the oven and let it sit on your counter for another hour to cool down.
The cheesecake might form that telltale crack in the top. Don't worry. You are going to cover it with the fruit before you serve it.
Cool the cheesecake in your refrigerator overnight. You don't need to cover it. (You can serve this the same day if you chill it at least 5 hours, but cheesecake actually tastes best on day 2 or day 3, after the flavors have had a chance to meld.)
Take the cheesecake out to decorate it. First, run a sharp knife around the edge of the cheesecake and then unlock the spring on the pan. Pull off the pan rim and place your cheesecake (with the metal bottom intact) on a pretty platter. Then open your raspberries and pick through them to make sure you don't have any "fuzzy moldy" ones. Starting in the center, pour the raspberries on top of the cheesecake. Don?t get too picky about how they arrange themselves. It's the natural look that counts. Do the same with the blackberries. You're sort of trying to have a mountain of fruit in the middle and let some of the rim of the cheesecake remain fruitless. Balance the sprigs of currants on top. They are sort of the crowning ornament.
Your cheesecake is ready. Continue to cool it until 30 minutes before you serve it Thirty minutes before serving, take it out of the refrigerator. Cheesecake always tastes more full-bodied if it's had a chance to warm up a bit. If it's refrigerator cold, it's too hard to taste the real flavor. My rule of thumb is to take the cheesecake out of the refrigerator when I put the dinner on the table so it has a chance to sit before I cut it.