Combine diced strawberries, sugar, and lemon juice in a small saucepan over medium heat. Cook, stirring occasionally, until the berries break down and release their juices, about 5-7 minutes. The mixture should look soupy and the berries soft but not completely mushy.

Stir the cornstarch slurry into the simmering berries. Cook for 1-2 minutes more, stirring constantly, until the mixture thickens slightly and turns glossy. Remove from heat and let cool completely to room temperature, about 15 minutes. (You can speed this up by transferring to a shallow bowl and refrigerating.)

In a medium bowl, beat the softened cream cheese with an electric mixer on medium speed until completely smooth and no lumps remain, about 2 minutes. Scrape down the bowl once halfway through.

Add the marshmallow fluff and vanilla extract. Beat on medium-low speed until fully combined and fluffy, about 1 minute. The mixture will be thick and sticky.

With the mixer on low, slowly pour in the cold heavy cream. Once incorporated, increase to medium-high and whip until the mixture lightens and holds soft peaks, about 2-3 minutes. Do not overbeat or it will become grainy.

Use a rubber spatula to fold in the 1/4 cup graham cracker crumbs until just distributed. This adds subtle texture and that signature cheesecake flavor.

Transfer the cheesecake mixture to a wide, shallow serving bowl. Dollop spoonfuls of the cooled strawberry compote across the surface, then use a knife or skewer to swirl it decoratively. Leave some white cheesecake visible for contrast. Sprinkle with extra graham cracker crumbs if desired.

Serve right away with fresh strawberries and graham cracker pieces for dipping, or refrigerate for up to 2 hours to firm up slightly. The dip will keep covered in the refrigerator for 3 days, though the swirl may blend over time.