Mix graham cracker crumbs with melted butter and 2 tablespoons sugar in a bowl until it looks like wet sand. Press this mixture firmly into the bottom of a 9-inch springform pan, making sure it covers the entire base. You want it packed down so it holds together when you slice it. Refrigerate the crust while you prep the filling.
Remove cream cheese from the fridge 30 minutes before you start—softened cream cheese whips way easier than cold stuff. Beat it with an electric mixer on medium speed for about 2 minutes until it gets smooth and creamy. Add 1/2 cup sugar and salt, then beat another 2 minutes until totally combined and fluffy.
In a separate bowl, whip the heavy cream and vanilla powder until stiff peaks form. This takes about 3-4 minutes with an electric mixer, and you'll know it's done when you can create peaks that stand up straight.
Gently fold the whipped cream into the cream cheese mixture using a rubber spatula. Do this in two batches so you don't deflate all that air—I usually fold gently until I see no streaks of white, which takes about 30 seconds per batch.
Pour half the filling into your chilled crust and smooth the top with a spatula. Then spread all the strawberry jam over it, leaving about a half-inch border around the edges. Top with the remaining filling and smooth it out nice and even on top.
Toss diced strawberries with powdered sugar and lemon juice in a small bowl. Let them sit for 5 minutes so the juice releases and creates a glaze (this is the secret to keeping them pretty).
Arrange the glazed strawberries on top of your no bake strawberry cheesecake in whatever pattern makes you happy. Refrigerate for at least 4 hours, but honestly overnight is better so everything sets perfectly and flavors marry together beautifully.