Preheat the oven to 325 degrees. Line a 9-inch springform pan with parchment paper and set it aside. Combine the crushed graham cracker crumbs and melted butter in a medium bowl. Stir until the mixture resembles wet sand. Press the crumb mixture firmly into the bottom and up the sides of the prepared springform pan.

In the bowl of a stand mixer, beat the softened cream cheese and sugar together until completely smooth with no lumps. Scrape down the sides of the bowl frequently. Add the eggs, mixing well and scraping down the sides after each one.

Mix in the lemon juice, vanilla, and sour cream until fully combined. Add the flour and mix once more. Finally, add the strawberry jam and mix thoroughly, scraping down the bowl to make sure everything is evenly incorporated.

Pour and smooth the filling into the prepared crust. Bake for 50 to 60 minutes, until the edges are set but the center still has a slight jiggle to it. Remove the cheesecake from the oven and allow it to cool to room temperature on the counter. Transfer it to the refrigerator to chill for at least 3 to 4 hours, or overnight if you want to make it ahead.

Combine the diced strawberries and strawberry jam in a small saucepan over medium-low heat. Stir frequently for about 10 minutes until the strawberries start to break down and the sauce thickens. Add the halved strawberries and heat for just 2 to 3 minutes — you want them to warm through and combine with the sauce without breaking down into mush. Allow the topping to cool in the fridge until ready to use.

Pour the cooled strawberry topping over the fully set cheesecake and spread evenly. Chill until ready to slice and serve.