array_chunk_min.php

<?php
function array_chunk_min($list,$minSize){
	$cnt = count($list);
	if($cnt <= $minSize){
		return [$list];
	}

	$lastChunkSize = $cnt%$minSize;
	if($lastChunkSize > 0){
		$chunks = array_chunk(array_slice($list, 0, $cnt-$lastChunkSize),$minSize);
		$lastChunk = array_slice($list, $cnt-$lastChunkSize,$minSize);
		$cntChunks = count($chunks);
		$chunks[$cntChunks-1] = array_merge($chunks[$cntChunks-1],$lastChunk);
	}else{
		$chunks = array_chunk($list, $minSize);
	}

	return $chunks;
}
print_r(
	array_chunk_min(
		range(1,75),20
	)
);