This tip comes from my incredibly talented older sister Marianne. She can create things out of paper that make you wonder why she hasn't made millions. Anyway, one day we were together and she was about to cut into a pan of brownies. I don't remember what we were talking about or how it came up but I distinctly remember her matter of factly saying, "you need a plastic knife to cut brownies, but everyone knows that". I remember thinking, um, I didn't.
The other day when I made a brownie like treat her wise words popped into my head and that little plastic knife worked like a dream! No more clumps of goo coming up or sadly shaped jagged squares, instead it created perfectly square bars and the knife even came out clean. I imagine it would work on lemon squares or any type of gooey treat that needs cutting. Give it a try and think of my awesome sister when you do.