Are you not aware of the different forms of English? There are several differences between American English and British English, “spelled” and “spelt” being one example.
Collins and Merriam-Webster are both American English dictionaries, and the Oxford English Dictionary is a British English dictionary.
It depends whether you’re English or American. Spelt is English.
Spelt is also a grain, a variant of wheat.
Yeah, one of the earliest cultivars
Spelt is not proper English.
Edit: I retract Collins as a trustworthy source.
Are you not aware of the different forms of English? There are several differences between American English and British English, “spelled” and “spelt” being one example.
Collins and Merriam-Webster are both American English dictionaries, and the Oxford English Dictionary is a British English dictionary.
Of course it is!