Press graham cracker crust into a 9x9-inch baking dish lined with parchment paper. Mix the cracker crumbs with melted butter and ¼ cup of the granulated sugar. Press down firmly with the bottom of a measuring cup so it stays compact, then refrigerate while you make the filling.

Beat softened cream cheese on medium speed until completely smooth and creamy, about 2 minutes. Scrape down the bowl and add the egg, blending until just combined. Don't overbeat or you'll incorporate too much air.

In a separate bowl, whip the cold heavy cream with the remaining ¼ cup granulated sugar and powdered sugar until stiff peaks form. This takes about 3-4 minutes with an electric mixer. The peaks should stand straight up when you lift the beaters.

Gently fold the whipped cream into the cream cheese mixture in two additions. Use a rubber spatula and work slowly so you don't deflate all those air bubbles you just created. The batter should look light and fluffy.

Stir in the lemon zest and vanilla powder until everything's evenly distributed. Fold in the fresh blueberries gently so they stay whole and don't bleed into the filling. I learned this the hard way after overstirring and ending up with purple cheesecake.

Spread the filling over the chilled crust in an even layer. Tap the dish gently on the counter a few times to release any air pockets hiding underneath. Refrigerate for at least 4 hours, though overnight is honestly better.

Once set, run a warm knife around the edges and cut into 12 squares. Wipe the knife with a damp paper towel between cuts so you get clean edges instead of dragging filling everywhere.