What to do when sides of tart crust collapse?
Not sure if it is the fault of the recipe, using non-stick spray on tart pan (as directed), and non-stick mini-tartlet pans (for extra crust), or what, but all three of my tart crust sides collapsed during the initial browning phase---before adding the filling. Anyway to shore up the sides so I can actually fill the thing? Also, if there are cracks in the bottom (small), will the liquid spill through and stick? Any way to seal those cracks---i.e. with butter?
Butter tart crust edges tend to collapse. It's just the nature of the beast.
If your tart shells are already prebaked, it's probably too late to try to make the sides higher. If you have at least some edge, I'd just go ahead and fill them. I'm often surprised that even with a collapsed edge my tarts seem to accept more filling than I think they will.
Did you use beans or pie weights when you prebaked? It sometimes helps if you push most of the beans or weights toward the edge of the tart pan rather than just have them in an even layer. I've also been known, part way through the prebake, to remove the foil or parchment along with the weights and use my fingers to push the crust farther up the sides before continuing the prebaking. Another method for creating a somewhat higher edge is to not trim the tart crust even with the tops of the pan but to trim the crust so that you can fold over the edges and still have about an eighth of an inch of dough above the pan (much as you do with a pie crust). The edges still collapse somewhat, but not as much.
I wouldn't worry too much about the cracks as long as they're small and your filling is somewhat thick. If you're worried about it, and if it's appropriate for your filling, you could always seal the bottom with some warmed and stirred apricot or other jam.
I am a neurotic type-A pie baker (if there is such a thing... long story; couldn't bake anything else correctly so I spent a few years trying to master the art of crusts)
what is your crust? Purchased or home-made: shortening, butter?How thick did you lay it down? Too thin will crumble immediately
Consider not using the non-stick spray for starters. If homemade, there should be enough fat in the crust for it to separate easily when baked... less pretty, but more secure...
Problem may be caused by natural shrinkage. I use aluminum foil and punch holes in it, removing crust from the oven periodically to flatten and smooth the crust back down (cover the sides, too, of course, especially if that's where your problem is). Pie weights would work too, rather than smoothing while baking; but I've never seen the need to buy them. Browning will not be a problem because an egg or butter mixture will make edges nice and shiny brown in the filled baking stages.
JoanN is right about the filling and sealing... the sugar will form a natural seal... I've also been known to bake a pre-filling in with a jam or caramel sauce to do the same thing... Let me know more particulars, and I'll have some better information for you.
What kind of recipe did you use? A sucre dough should hold up to blind-baking before being filled, whereas a crostata type of dough(where the butter is cut in last, rather than creamed first)won't hold it's shape unless it filled and the edges are formed around the filling.
The standard crostata dough I use doesn't need to be blind baked, it gets plenty browned and crispy with the single baking time. Happy to give you the recipe if you like, although it is more crispy and flaky than a sucre (3:2:1) dough.
As far as little cracks in the bottom/sides of your blind baked shell, save the dough scraps from when you are rolling out your dough and smear a little bit of the raw dough into the cracks of your baked shell to dam up the holes. This will then bake when you put it back into the oven with your filling. Try to patch it when the shell is still warm and you will be able to get a thinner layer of raw dough.