Use cream cheese softened to room temperature for a smooth filling., Avoid overmixing eggs to maintain a creamy texture., Chop rhubarb into small pieces for even flavor and easier eating., Slice with a sharp knife, wiping it clean after each cut for neat edges., Always line pan with parchment paper for easy removal and to keep bars intact., Substitute fruits such as strawberries, blueberries, or raspberries; drain thawed frozen fruit well to prevent sogginess., Try different crusts like graham cracker or almond meal for variation., Reduce sugar for less sweetness, noting texture changes may occur., Add crumbly streusel topping or swirl in fruit jam for extra flavor and appearance., Store bars in airtight container in fridge up to 4 days; freeze individual squares up to 2 months., To serve, let bars come to room temperature or warm briefly in microwave or oven.