In a medium bowl, combine graham cracker crumbs and melted unsalted butter, mixing until the mixture resembles wet sand. Press this mixture firmly into the bottom of a lined 9x9 inch pan, ensuring an even layer. Place the crust in the refrigerator to chill for at least 15 minutes while you prepare the filling.

Using a hand mixer or stand mixer, beat the softened cream cheese in a large bowl until smooth and creamy. Gradually add powdered sugar, vanilla extract, and sour cream, mixing until fully combined. Then, in a separate bowl, whip the heavy cream until stiff peaks form and gently fold it into the cream cheese mixture, ensuring a fluffy consistency.

In a small saucepan, combine diced fresh strawberries with a sprinkle of sugar and let them sit for about 5 minutes to release their juices. Heat the mixture over medium heat, stirring gently until the strawberries soften, which should take about 5-7 minutes. Mix cornstarch with water to create a smooth paste, then add this to the strawberry mixture, stirring until it thickens. Allow it to cool to room temperature.

Retrieve the chilled graham cracker crust from the refrigerator, and carefully spread the creamy cheesecake filling over it, smoothing it into an even layer. Once spread, take the cooled strawberry mixture and dollop it on top of the cheesecake layer, distributing it evenly. Optionally, sprinkle extra graham cracker crumbs over the strawberry topping for additional crunch.

Cover the assembled Chocolate Strawberry Crunch Cups with plastic wrap or a lid to prevent drying out. Refrigerate for at least 4 hours, or ideally overnight, allowing the flavors to meld and the filling to firm up.

When ready to serve, use the parchment paper overhang to lift the dessert from the pan gently. For neat and beautiful slices, dip a sharp knife into hot water, wipe it dry, and cut through the cups. Top each cut piece with a fresh strawberry slice for an irresistible finishing touch.