Preheat your oven to 325°F (160°C) and prepare a muffin tin by lining it with paper liners.
In a medium mixing bowl, combine the graham cracker crumbs and 1/4 cup of sugar. Pour in the melted butter and mix until the crumbs are evenly coated.
Press about one tablespoon of the crumb mixture into the bottom of each muffin cup and bake for 10 minutes. Allow to cool completely.
In another medium bowl, beat the softened cream cheese until smooth. Gradually add 1 cup of sugar and the vanilla extract, mixing until fully combined.
Add the eggs one at a time, mixing on low speed just until incorporated.
In a small saucepan, combine the mixed berries and lemon juice. Cook over medium heat until the berries soften, then add the cornstarch and stir until thickened. Allow to cool slightly.
Pour the cream cheese mixture over the cooled crusts, filling each cup about two-thirds full.
Drop dollops of the berry mixture on top and swirl gently with a toothpick.
Bake for 18-20 minutes, or until the centers are set but still slightly jiggly.
Allow to cool to room temperature in the muffin tin, then refrigerate for at least 4 hours or overnight.
Notes
Serve with whipped cream and fresh berries for a beautiful presentation.