In a medium bowl, combine crushed graham cracker crumbs, melted unsalted butter, and dark brown sugar until the mixture resembles wet sand. Press the mixture firmly into the serving cups to form a base.

In a chilled mixing bowl, beat ½ cup of heavy whipping cream on medium-high speed until stiff peaks form, about 3-5 minutes. Refrigerate the whipped cream until needed.

In another large bowl, beat the room temperature cream cheese and granulated sugar until smooth. Add sour cream, powdered sugar, and vanilla extract, mixing until just combined.

Gently fold the whipped cream into the cream cheese mixture using a spatula. Spoon 1/6 of the filling into each cup over the crust.

Cover the cups and chill in the refrigerator for 4-6 hours or overnight.

Once set, spoon about 2 tablespoons of strawberry jam into each cup and swirl gently for a marbled effect.

Beat the remaining heavy whipping cream with additional powdered sugar and vanilla extract until stiff peaks form. Pipe this whipped cream on top of the jam layer.

Garnish with sliced strawberries and optional dark chocolate shavings. Serve immediately or store in the fridge.