Formula that shows commonly sold trends across multiple sales orders

I am trying to compose a formula that tells me the most commonly sold products with other products, so i know what I should order to replenish stock. Lets say I have the following 4 sales
Sales order number/ products sold (it would be on separate lines)
0001 Apples and Milk
0002 Apples and Milk
0003 Nectarines and News Paper
0004 Bananas and Milk


When I go to reorder apples, I want a column that tells me that Milk was ordered twice with it, so I can kind of profile my stock based on the number of orders that hit that criteria (in this case, 2). This is a simplistic example, and I thought about a kind of countif formula but can't quite get it. Any thoughts would be appreciated.

how does this look in a sheet
are all the orders on separate columns
or a list of all orders numbers

a sample spreadsheet maybe useful

I suspect there maybe 100s of variables here
apples may be purchased with 50 other items and some of those maybe common on every order
ie
0001 Apples , Milk , Nectarines , News Paper , Bananas
0002 Bananas and Apples and milk
0003 Milk sugar cheese
0004 Cheese newspaper milk
0005 Nectarines, cheese , sugar