Anyone else have a finicky 2-year-old who LOVES cheese today but will despise it tomorrow? Me too. For some reason serving food in creative ways makes ALL the difference in my house. My daughter will try almost anything as long as it is artfully arranged. Lately I've been trying to hold myself accountable to offering a variety of foods at each meal (something I used to be good at doing but have fallen off the make with lately). Serving meals in muffin tins helps so much because there are six or twelve cups that need to be filled. Here are a few of the meals I've served lately.
This would be fun with themes too. For example, you could serve food of all one color or shape. My daughter loves fun-shaped foods. One of the things she requests the most often are "cumber fwies" (cucumber fries). I just cut veggies into matchsticks and call them fries, and it works! She's also pretty fond of moons (half circles), circles, squares, and calling things fun names. She calls broccoli "baby trees" and eats a ton.
Think outside of the box, too. You could fill one cup with peanut butter, hummus, nuts, raisins, yogurt, etc.
Hope this idea helps you get some food with nutritious value into your picky preschoolers!