Not being an expert, I'm in no position to judge between these two historians, Bede and Hutton. However Bede cites no earlier sources, but Hutton *did* go back to earlier sources, and found no evidence of any such goddess, or of a cognate figure, in any of the extant Norse or Germanic texts.
So everybody's source is ultimately Bede, who is here challenged.
The fact that these festivals are not referenced in the NT is of little relevance. There's no rule that all Christian practices have to be found in the text. If that were so, we could not have church buildings, church weddings, church funerals, or even the church's Book, the Bible, since there was a church for decades before the books of the NT were completed, and for centuries before those writings were officially collected and recognized as the canon of Sacred Scripture.
There was a Pascha celebration --- and others --- before there was a (complete) Bible.
Some debate has occurred over whether or not the goddess was an invention of Bede's, particularly in the 19th century before more widespread reconstructions of the Proto-Indo-European dawn goddess. Writing in the late 19th century, Charles J. Billson notes that scholars before his writing were divided about the existence of Bede's account of Ēostre, stating that "among authorities who have no doubt as to her existence are W. Grimm, Wackernagel, Sinrock [sic], and Wolf. On the other hand, Weinhold rejects the idea on philological grounds, and so do Heinrich Leo and Hermann Oesre. Kuhn says, 'The Anglo-Saxon Eostre looks like an invention of Bede;' and Mannhardt also dismisses her as an etymological dea ex machina." Billson says that "the whole question turns [...], upon Bede's credibility", and that "one is inclined to agree with Grimm, that it would be uncritical to saddle this eminent Father of the Church, who keeps Heathendom at arms' length and tells us less of than he knows, with the invention of this goddess." Billson points out that the Christianization of England started at the end of the 6th century, and, by the 7th, was completed. Billson argues that, as Bede was born in 672, Bede must have had opportunities to learn the names of the native goddesses of the Anglo-Saxons, "who were hardly extinct in his lifetime."[14]Ref: https://en.wikipedia.org/wiki/%C4%92ostreWriting in the late 20th century, Rudolf Simek says that, despite expressions of doubts, Bede's account of Eostre should not be disregarded. Simek opines that a "Spring-like fertility goddess" must be assumed rather than a "goddess of sunrise" regardless of the name, reasoning that "otherwise the Germanic goddesses (and matrons) are mostly connected with prosperity and growth". Simek points to a comparison with the goddess Rheda, also attested by Bede.[15]
Scholar Philip A. Shaw (2011) writes that the subject has seen "a lengthy history of arguments for and against Bede's goddess Eostre, with some scholars taking fairly extreme positions on either side" and that some theories against the goddess have gained popular cultural prominence. Shaw, however, notes that "much of this debate, however, was conducted in ignorance of a key piece of evidence, as it was not discovered until 1958. This evidence is furnished by over 150 Romano-Germanic votive inscriptions to deities named the matronae Austriahenae, found near Morken-Harff and datable to around 150–250 AD". Most of these inscriptions are in an incomplete state, yet most are in a complete enough for reasonable clarity of the inscriptions. As early as 1966 scholars have linked these names etymologically with Eostre and an element found in Germanic personal names.[16] Shaw argues against a functional interpretation from the available evidence and concludes that "the etymological connections of her name suggests that her worshippers saw her geographical and social relationship with them as more central than any functions she may have had".