"Livre de recettes"
Dictionary.com gives receipt as the primary definition of recette (which is the usage that I am familiar with because of the commercial context within which I see it). Then recipe followed by formula.
Google Translate graphs recipe as the most common usage followed by receipt. Formula doesn't show up on their scale. I assume that Google only references internet usage. Considering all the digitized books, magazines, web sites etc. that they process that would be pretty extensive.
Please see above comment from Sitesurf which addresses this specific issue.
Des is plural when used as some.
Des is also used as a contraction of de les when referring to of the/ de les.
De is used when referring to of .
The sentence refers to recipes in general book of recipes.
Thus Livre de recettes is literally book of recipes or more commonly in English recipe book .
This sentence does not refer to particular recipes known to the writer and the reader book of the recipes. If it did it would be livre des recettes.
And clearly it does not mean book some recipes which is what it would mean if you use des as having to be plural because it is the plural indefinite article as you would want it to be.