Help w puff pastry shrinkage!

Thank you for your responces! Will definitely try your suggestions on my next tart.

Yep - 15 minutes is quite a lot of rolling time. As boulangere suggested, I think working a little more quickly might be the best way forward.

You're perfectly correct to refrigerate it before baking - a good 30 minutes will help. The miracle of puff pastry is that it's entirely steam leavened. When it loses that moisture during baking, it makes sense that it's going to shrink a bit. The key is to never let it get so soft that it gets mushy. When that happens, the butter is softening too much and water is leaching out into the dough. When more water than originally intended invades the dough, more gluten (the protein in flour) is formed, especially during all that rolling. More gluten formation leads to tougher pastry which will shrink even more as the gluten tightens up in the high heat of the oven. So, be sure your work surface is adequately floured, work quickly, and refrigerate often during the rolling/shaping/cutting processes.

Do you work it or handle it too much? That will cause shrinkage.