In a saucepan over medium heat, combine half of the diced strawberries with lemon juice. Cook for about 5–6 minutes until the strawberries burst, releasing their juices and becoming syrupy.

Add brown sugar and cornstarch to the strawberry mixture, stirring to combine. Return to the heat and cook for an additional 2 minutes or until the sauce thickens slightly. Incorporate vanilla extract for added flavor.

Preheat your oven to 325°F (165°C) and prepare a cupcake pan by lining it with paper liners.

In a mixing bowl, combine graham cracker crumbs and sugar with melted butter. Press this mixture firmly into the bottom of each cupcake liner.

In a separate bowl, mix together flour, sugar, and a pinch of salt for your streusel topping. Drizzle in some melted butter and mix until you achieve a coarse crumb texture.

In a large mixing bowl, beat room-temperature cream cheese with sugar, flour, and vanilla extract until smooth. Gently fold in the beaten egg until just incorporated.

Fill each crust halfway with cheesecake filling, then spoon a layer of the cooled strawberry sauce on top. Finish by sprinkling the streusel topping over each mini cheesecake.

Place the filled cupcake pan in the preheated oven and bake for 30–35 minutes. Let them cool in the pan for 20 minutes before transferring to a wire rack.

Refrigerate the mini strawberry cheesecakes for at least 2 hours before serving.