Line pie plate with prepared pie crust and crimp edges.
Spread Wild Maine Blueberry Jam or Holiday Jam evenly over bottom of pie crust.
In a small bowl combine the sugar, flour and salt. Mix thoroughly.
Combine the sour cream, egg, and vanilla in a medium size bowl and mix. Add the flour mixture and mix.
Peel, core and slice the apples (approximately 1/4-inch thick) and add them to the sour cream mixture. Toss and coat the apples, then spread them evenly in the pie crust.
Bake the pie at 425° F for 10 minutes. Reduce heat to 350° F and bake an additional 30 minutes.
While pie is baking, prepare the crumb topping by combining the flour, sugar, and cinnamon in a bowl. Cut in the butter until topping resembles coarse meal.
After pie has cooked 30 minutes top with crumb topping and bake an additional 15-20 minutes.