Both come from the latin recepta
, but apparently Spanish one evoluted differently. However, from what I see in the RAE recepta
is still accepted: http://dle.rae.es/recepta:
recepta.
(Del lat. recepta, t. f. de -tus, recibido).
f. Libro en que se llevaba la razón de las multas impuestas por el Consejo de Indias.
f. ant. Receta médica.
From what I see in Evolución histórica del latín#Rivus non ríus, síbilus non sífilus it was common from the /p/
to "fall", so it might be the reason.
See the etimology in Spanish and English in the following pages.
Etimologias.dechile.net - receta:
La palabra "receta" viene del latín recepta y
significa "nota escrita detallando un procedimiento". Sus componentes
léxicos son: el prefijo re- (reiteración), capere (capturar,
agarrar, tomar), más el sufijo -to (que ha recibido la acción). Ver:
prefijos, sufijos,
otras raíces latinas, receptor y recipiente.
Dictionary.com - receipt:
late 14c., "act of receiving;" also "statement of ingredients in a
potion or medicine;" from Anglo-French or Old North French receite
"receipt, recipe, prescription" (c.1300), altered (by influence of
receit "he receives," from Vulgar Latin *recipit) from Old French
recete, from Latin recepta "received," fem. past participle of
recipere (see receive ). Meaning "written acknowledgment of money or
goods received" is from c.1600.
As a funny thing, in Catalan it is said just recepta
.