All the fractions you'll need for a cookbook are found in the "Latin-1
Supplement" range of Unicode (half and quarters) and in the "Number
Forms" range (thirds, eighths -- also fifths and sixths).
Quite a few fonts, including Times New Roman, have the thirds and
eighths, and many have only the eighths.
To find them, go to Insert Symbol, and in the upper right dropdown
select one or the other of the Unicode ranges. You'll see the
fractions if they're available in the currently selected font.
While you're in the Insert Symbol panel, you can assign Keyboard
Shortcuts to them if you'd like (button at middle bottom). Or, you can
make Autoformat As You Type entries so that typing 1/8 automatically
gives the one-eighth fraction, etc.
