Need tips for fussy eaters

[Kazonia]

I have three children. 7 5 and 2. My 2 year old will eat pretty much everything I put infront of him. Like my older 2 used to do when they were his age. But the older they got the more fussy they got and its driving me insane.
Last night I managed to get them to eat jacket potato with cheese and or beans for the first blooming time ever!!! And I was so pleased that they tryed it and kept eating it (be it to only get pudding cos I had baked a cake. But I cant bake a cake every day haha) I have tryed so hard. They dont get pudding unless they eat all there dinner. I never cook them. Alternatives. When I say like it or lump it they choose to lump it!! And so much food is getting wasted because of it.
What have you all tryed that worked!? I would really appreciate some advice

Give them what they will eat.
Give them a small portion of dessert.
Bribe them to try new things.
Let them be hungry.
No snacks and only water between meals.
Don't overly praise and never punish.
Start making smaller portions, or food you can easily freeze.
If they ate jacket potato and cheese etc they like it. They would have retched and cried if they didn't. They need to learn that not all food has to be their absolute and most delicious favourite, sometimes you eat stuff that's OK or just alright. So now you know there is one thing they will eat. Build on this.
Add or change an ingredient to stuff they will eat to get them to try it. They don't have to like stuff, just try it.
Involve them in cooking/shopping/meal planning etc.
And - wayyyyyyy easier said than done - shrug and say OK then if they won't eat. Try your absolute hardest to not let them hear you open the fridge door and swear furiously at a lettuce.
Eat at the table, they have to remain there at meal times whether they eat or not.

All/none of the above may be of any use.

There are thousands of children who basically live on thin air for years, only to eat well and healthily when they're older. It's infuriating but who said parenting was easy.

And lettuces are very forgiving.

Just it the food on the table and let them eat it or not eat it. If they can serve themselves even better. Try and make sure there's at least one 'safe' food.
Talk about anything but the food.
No cajoling, bribing, paying attention to whinging.
Make it clear they don't have to eat anything they don't like but they also don't need to make a fuss about food they don't want.
Just work on them sitting at the table, chatting and enjoying that time, the food part is secondary.