I think the more firm-handed approach quoted above would work well for some kids, but would NOT work for my sensitive, spirited, high-needs, likely gifted DD1. If I get too firm, she stops. If I try to rush her, she stops. Case in point, I am getting irritated that she refuses to get herself dressed and undressed. I have tried to get her to do something as simple as put her own socks on, and it becomes a huge power struggle. If I push, if I rush, she refuses. It's a delicate dance of getting her to think something was her idea all along.
One day, I'd had enough (and I WOH FT, nights, and have a 13 month old as well) and I said to her "You don't treat Daddy like this. You'd never speak to him like that. Pretend I'm Daddy today." We totally had a much, much easier day than we'd had in weeks, and a far better day than that day was headed.
Choices help. Telling her the next three things that are going to happen helps.
OP, I wanted to say thanks - it's not easy to "put it out there" that you're struggling with this stuff. So thanks for putting it out there.
With the pancake thing, for example, I'd probably say "Yum, pancakes sound like a great idea for breakfast! But, can you think of a nicer way to ask for them, a more polite way?" She almost 100% of the time will say "Mom, can we please have pancakes for breakfast, please, Mommy?" (yes, saying my name and please twice is her general speech pattern) and I'll say "You asked so nicely! We sure can have pancakes. Can help me make them?"
Helping in the kitchen is her big thing right now. Getting some kitchen time every day helps. Also, getting some outside time every day is huge, but very difficult for us right now since it's bitter cold, and we live in a condo with absolutely no yard. With the baby, I can't just take her to play at a park right now, either, since she wants to play when the baby's napping. Can't just leave the baby and take DD1 to the park! And neither of my kids have ever been on-the-go nappers.