Begin by crushing the graham crackers into fine crumbs using a food processor or by placing them in a zip-top bag and rolling with a rolling pin. In a medium bowl, combine the crumbs with melted butter until thoroughly mixed. Press this mixture firmly into the bottom of a 9x9-inch square pan to form a solid base, and then set aside to firm up while you prepare the filling.

In a saucepan over medium heat, combine 2 cups of chopped rhubarb with ½ cup of sugar. Stir occasionally, cooking for about 5-7 minutes until the rhubarb is softened and begins to break down. Once softened, remove from the heat and let the mixture cool slightly.

In a large mixing bowl, using an electric mixer, beat together 8 ounces of softened cream cheese with another ½ cup of sugar until creamy and smooth, about 2-3 minutes. Gently fold in the cooled rhubarb mixture.

Carefully pour the rhubarb cream cheese mixture over your prepared crust, spreading it evenly with a spatula. Tap the pan lightly on the counter to remove any air bubbles.

Cover the pan with plastic wrap and refrigerate for at least 2 hours, or until fully set.

Once chilled, remove the pan from the fridge, lift the bars out using the edges of the foil or parchment paper, cut into squares, and serve garnished with fresh berries or whipped cream.