Without knowing what he refuses, it is wide open to suggestions.. so be prepared for the list you're gonna get from all of us moms out here... LOL
You're right to consider that you don't want to spoil by making a "special" dinner for him. What I have always tried to do is just be sure that there is ONE thing on the plate that I know they will eat. Then let them have a bite of everything else. At least try one bite of one new thing.. then can eat/not eat from their plate whatever they want/don't.
At 3 yrs old, he should be asking for permission to be excused when he is done, so don't mention anything about what is on his plate until he has asked to be excused/or if he can be done. Then let him know that he needs to eat "one bite of ___", then he can get down.
You might try preparing things differently. Our kids always have liked grilled meats. You just have to cut it up before putting it on their plate. Grilled chicken or steak, our son even (yes at that age) liked grilled salmon! Or smoke some pork and do pulled pork with BarBQ sauce. You can nuke (steam) cut of zuchinni or yellow squash add a dash of Lawry's seasoned salt and pat of butter for some "different" veggies. They also preferred corn on the cob, rather than cut off the cob (they got to use those "special" corn-holders!).
Have you made a Pizza? What kid doesn't like that? Make half like you guys like it (don't forget the mushrooms!), and half how he'll eat it.. Buy one of those pre-made crusts and a jar of Ragu Pizza Quick, some mozz.cheese and go for it! (My husband LOVES it). Let olives be a side dish one night (our kids LOVE black and green olives). Peel and slice up a cucumber or wash some romaine lettuce leaves or baby carrots and let him dip them in some ranch dressing. My kids are MUCH more likely to eat a RAW veg than a cooked one. Will he eat a grilled cheese sandwich? You could put some ham in yours and serve with soup and oyster crackers (our kids like putting the crackers in their bowl).
Another thing we do with our kids is make chef salads... but put all his salad on a plate, without things touching.. a pile of lettuce, a pile of shredded or cubed cheese, some olives, cucumber slices, little ham rolls, turkey rolls, a slice of boiled egg, etc. then some ranch dressing to dip it all in...
What about quesadillas... just cook the chicken and cut it up into small pieces, then throw a tortilla on a pan, spread with some cheese, add the chicken pieces, fold and flip, (you can add peppers and onions or whatever to you and your husband's), let him dip it in sour cream...
Will he eat rice? You could crock pot some chicken and rice...
Our daughter actually began eating steamed broccoli at about that age. Just cut the tops off, rinse, put them in a bowl with some water, sprinkle some salt, and nuke for 5 min. (covered with wax paper). Then stir a pat of butter, or use a dash of lemon juice and stir.. At many restaurants you can get steamed broccoli with their kids' meal (as an alternative to fries).
Just a few ideas... best of luck.. now that mine are older, I STILL struggle with what to cook for dinner! We're always on the go and everything takes so LONG...