Burned Cookie Bottoms: With quick baking times, cookies can end up burning if they're in the oven even a few minutes too long. Keep in mind that cookies harden once they cool, so watch carefully and check on them when they're nearing the end of bake time. Make sure they're baking in the middle of the oven. If you end up with slightly burned cookie bottoms, turn them into sandwich cookies! Spread the burned bottoms with frosting, ice cream or whipped cream, and smoosh another cookie on top. A moist sandwich filling will soften the bottoms and hide the burnt taste. If they're super-burnt, they're going to be harder to rescue. Cut off the burnt part, chop the remainder into bits and see below for ideas on using broken cake or cookies.
Overflowing Batter: When making a new recipe, it can be easy to misjudge just how much your cake, breads or muffins will rise. A safe rule of thumb is never to fill your pan to the top; fill only about two-thirds or three-quarters of the way up. Place a baking sheet under your pan to catch any overflow during baking and you'll avoid messy oven cleanup. If your cake does overflow, simply cut around the edges; if they looked ragged or uneven, pipe frosting or stiff whipped cream around the outsides.
Burned Pie Crust: If your crust looks like it's getting too brown and the pie still has a long way to go, cover the crust with a pie crust shield or some aluminum foil. If your pie crust comes out of the oven too burned to serve, trim off the edge crust and pretend it never existed — there will still be plenty of crust to eat on the sides and bottom.
Broken Cake or Cookies: Broken cake or overly crumbly, brittle cookies can easily become the base for a delicious trifle or parfait. Layer broken cookie pieces or chunks of cake with any combination of fruit, ice cream, pudding or whipped cream and refrigerate until chilled. The crunchy or broken bits will become soft and flavorful, and trifle's so tasty that no one's going to be unhappy about it.
Cracked Cake Top or Pie Crust: Cracked tops may mean that your oven was too hot or your batter or dough was too dry. Dollop whipped cream or drizzle sauce over the cracks — we don't hear too many complaints about a little extra whipped cream.
Runny Frosting: If your frosting looks a little too much like a sauce while you're mixing, try mixing in extra confectioners' sugar (cocoa powder if it's chocolate frosting). If your kitchen is especially warm, try refrigerating or freezing the frosting until it firms up. If you've already begun icing your cake and the frosting is dripping off, try refrigerating the cake to harden and then continue.
Leaden Cake: Over-mixing your batter can often lead to dense, heavy cake. To ensure a fluffy texture, cream together your butter and sugar very well when called for, and then mix in the remaining ingredients very gently — only until just combined. If your cake comes out heavy, slice into pieces and soak in simple syrup, whipped cream or liqueur. You'll be adding more flavor while moistening the cake.