In a medium size bowl, combine the crushed cookies and softened butter. Mix well. Press this into the bottom of an 8" square springform pan, or a baking pan that has been lined with parchment paper or foil. If you use foil, spray the foil with cooking spray. Bake the crust at 350 degrees for 8 minutes.

While the crust is baking, place the cream cheese in a bowl. Beat the cream cheese with an electric mixer until it is smooth. Add in the eggs, sour cream, sugar and vanilla. Beat the mixture until it is smooth and creamy, about 3 minutes.

Once the Oreo crust has cooled, pour half of the cheesecake batter into the crust.

Microwave the strawberry preserves for about 30 seconds and mix it. Drizzle 1/2 cup of the warm strawberry preserves over the cheesecake batter. Pour the rest of the cheesecake batter in the pan. Drizzle the remaining 1/2 cup of strawberry preserves on top of the cheesecake batter. Using a knife, gently swirl the strawberry preserves back and forth to create a swirl pattern.

In a small bowl, combined the softened butter, sugar and flour until you have small crumbs. Sprinkle this topping on the top of the cheesecake batter.

Bake the cheesecake at 350 degrees for 40 minutes. The center of the cheesecake should be set and the edges very lightly browned.

Allow the cheesecake to cool for 30 minutes, then move the cheesecake to the refrigerator to set for at least 4 hours, but preferrably overnight. Once the cheesecake is cool, remove it from the pan and cut it into 16 squares.

Store the cheesecake bars in the refrigerator.

Serve with strawberries and whipped cream, if desired.