This is pretty simple, especially if you're just adding them manually. Might help to look at it formatted:

my @AoH = (
    {
        'key1' => 'value1', 
        'key2' => 'value2', 
        'key3' => [ # aref starts here
            {
                'var1' => 'val1', 
                'var2' => 'val2',
            }, 
            {
                new_hash_key1 => 'val1',
                new_hash_key2 => 'val2'
            }, 
        ],
    },
);
[download]