Preheat oven to 325ºF. Spray and line an 8 x 8-inch square pan with parchment paper.
In the bowl of a food processor, blitz together the flour, oats, sugar, salt and butter to create the crust. Blend for about 45-60 seconds or until the mixture comes together in large crumbles. It should hold together when gently squeezed.
Pat the crust mixture into the prepared pan and smooth into an even layer. Bake until golden, about 25 minutes.
When the crust is nearing doneness, wipe the food processor bowl clean. Add in the cream cheese, sugar, sour cream, vanilla extract and lemon juice. Blend until completely smooth, about 30-45 seconds. Scrape down the sides of the bowl, add in the eggs and pulse until just combined.
Pour the batter into the baked crust, tapping gently to pop large air bubbles.
Bake for 35-37 minutes, until the center no longer jiggles and the edges are beginning to turn golden. Let cool completely at room temperature before refrigerating. Just before serving, slice into 16 squares and generously garnish with fresh berries and lemon zest. Serve chilled.