The best way to slice a pie is with a sharp chef's knife that has been heated in boiling water. Wipe the knife with a towel before use. When used for slicing, the warm knife will dissolve the sugars in the pie, resulting in clean slices.
To serve only one slice, cut two adjacent pieces of pie. This will allow one slice to be removed more easily. When serving multiple slices, cut the entire pie before scooping pieces out. If the pie contains sticky ingredients, using a cold knife will result in clean cuts. Pies with crumbly ingredients and air pockets may be sliced easier using a buttered knife. A good way to slice cutting sheet cakes is to use waxed dental floss.