Depending on the parchment paper you use, your oopsie may stick a little. If that is the case, let it cool on the paper, then slide a large knife under it to ease it off.
If you make it in advance, or you use only half, allow it to cool completely, and store in an airtight container in the fridge for up to 3 days.
Re-heat to restore crispness.
Metric kitchen scales are an inexpensive yet invaluable gadget to enable accurate measurement of ingredients. Store them upright in a cupboard or over your worktop and they'll only take up a tiny bit of space. Click
HERE for the ones I use (UK Link). For U.S. option click
HERE.