I have tried greasing the tin and not lining with baking parchment. But the flapjack sticks to the tin and is impossible to get out without destroying most of it. I've also tried lining the tin with baking parchment and greasing the baking parchment. But the flapjack stuck so hard to the baking parchment it was impossible to peel it off and again I had to throw most of my flapjack in the bin! I'm so upset. What can I do?