In a medium-sized mixing bowl, combine cream cheese and sugar and stir until smooth and creamy.

Add sour cream and vanilla extract and stir until thoroughly combined.

Line a small baking sheet with wax paper and dollop cream cheese mixture by 2-teaspoon sized portions onto sheet. Place in freezer while you prepare cookie dough.

In a large mixing bowl, combine butter and sugars and use an electric mixer to cream together until light and fluffy.

Add egg and vanilla extract and stir well, until thoroughly combined.

In a separate, medium-sized bowl, whisk together flour, graham cracker crumbs, cornstarch, baking powder, baking soda, and salt.

Gradually stir dry ingredients into wet with mixer on medium-low speed. Scrape sides and bottom of the bowl periodically to ensure ingredients are thoroughly combined. Cover bowl with plastic wrap and chill in the refrigerator for 30 minutes.

Preheat oven to 375F (190C) and finely chop white chocolate (if using). Set aside.

Remove dough from the refrigerator and scoop a 2-Tablespoon-sized portion. Roll into a ball and use your thumb to make a large crater in the center. Spoon 1 ½ teaspoons of strawberry jam into the crater then remove a portion of cream cheese filling from the freezer and nestle it into the jam. Scoop another 2 Tablespoon-sized portion of dough and use this to cover the cheesecake filling and roll between your palms to make a smooth ball.

Lightly press white chocolate pieces into the surface of cookie dough ball.

Place on a large plate or wax paper lined baking sheet and chill in the freezer for 10-15 minutes before baking. Repeat with remaining dough, jam, filling, and chocolate.

After dough has chilled, place on parchment paper lined baking sheet, spacing at least 2" apart. Transfer to center rack of 375F (190C) preheated oven and bake for 14-15 minutes.

Allow cookies to cool completely on baking sheet before enjoying.