Lucky for me my toddler didn't just eat toast. It was toasted PB sandwiches for her and as she grew older, her tasted refined to include that Torta bread that can only be found in Costco's. Buy that, get some Boirsin cheese and/or butter, toast in toaster over, spread cheese or butter and give to now 7yr old toddler. She's done until a few hours later when she wants bread and butter for dinner.
My oldest was insanely picky. Thankfully we had a few things she would eat that actually constituted a semi-balanced meal. It's just that she ate it every day. Apples - must be red delicious and cut just right. Grilled Chicken - plain. Broccoli - steamed and plain. Wheat Toast - plain. Hard Boiled Egg - over boiled so the yolk was grayish/chalky - gag. Carrot Sticks. Brie - with rinds so she could poke her carrot sticks into it. Celery - with peanut butter and raisins.
The big breakthrough for her came at a fair. I ordered a turkey leg and offered her a bite - totally expecting her to refuse to try it. She loved it and insisted on carrying it with both hands (too heavy for one) like a little caveman. She was practically gnawing on the bone and wouldn't let us throw it away until we stood around the trash bin and sang that Goodbye song from Sound of Music. Weird runs in the family, I guess.
My youngest one was a micro-preemie and has always been tiny. She would just happily scarf down anything you put in front of her. She's 17 now and I think could actually win competitive eating contests even though she's maybe 100lb soaking wet. We went to a Brazilian Steakhouse (where they just keep coming by with meat) over the weekend. She must have packed away 3lbs of filet mignon on top of huge helpings of salad and potatoes. An hour later she ate a huge slice of cheesecake. That night, I heard her rummaging in the fridge for a midnight snack. No one knows where she puts it...