well, you can use the following my class that I have written with help of community to split List into parts

public with sharing class Lists {

    public static List<List<Object>> doPartions(List<Object> records, Integer size, Type destType){
        checkNotNull(records);
        checkArgument(size > 0);
        checkNotNull(destType);
        return new Partition(records, size, destType).doPartition();
    }

    private static void checkNotNull(Object reference) {
        if (reference == null) {
            throw new NullPointerException();
        }
    }

    private static void checkArgument(Boolean expression) {
        if (!expression) {
            throw new IllegalArgumentException();
        }
    }

    private class Partition{
        private List<Object> items;
        private Integer splitSize;
        private Type destType;

        Partition(List<Object> records, Integer size, Type destType){
            this.items = records;
            this.splitSize = size;
            this.destType = destType;
        }

        List<List<Object>> doPartition(){
            List<List<Object>> result = (List<List<Object>>)destType.newInstance();
            List<Object> protoList = items.clone();
            protoList.clear();
            List<Object> tempList = protoList.clone();
            Integer index = 0, count = 0, size = items.size();
            while(index < size) {
                tempList.add(items.get(index++));
                ++count;
                if(count == splitSize) {
                    result.add(tempList);
                    tempList = protoList.clone();
                    count = 0;
                }
            }
            if(!tempList.isEmpty()) {
                result.add(tempList);
            }
            return result;
        }
    }

    public class IllegalArgumentException extends Exception {}
}

unit-tests

@isTest
private class ListsTest {

    @isTest
    static void testCorrectPartions(){
        List<Integer> records = new List<Integer> {
            1, 2, 3, 4, 5
            };
        Test.startTest();
            List<List<Integer>> actual = (List<List<Integer>>) Lists.doPartions(records, 2, List<List<Integer>>.class);
        Test.stopTest();
        System.assertEquals(3, actual.size(), 'Incorrect number of partions');
        Integer tempNumber = 1;
        for(List<Integer> itemsActual :actual){
            for(Integer numb :itemsActual){
                System.assertEquals(tempNumber, numb, 'Order of elements isn\'t saved');
                ++tempNumber;
            }
        }
    }
}