In the castle shop there are also little books with old castle recipes. For 2,.50 you can experiment to your hearts content!
How about recipes for stewed cucumber, eel soup, almond cake, buttermilk sauce with bacon and boerenjongens (raisins in gin).
there's a little shop in the castle that sells seeds from plants grown in the castle vegetable garden. Just one euro per sachet. Should be fun to watch them sprout next year. I bought a few varieties of peas and beans. I'm hopeless at this sort of stuff but I like eating them.