Serve leftover food from your previous night's dinner.
Serve chopped up cooked veggies that you can prep at the weekend along with instant mashed potatoes.
Prepare something simple ahead of time like savory bread pudding with egg, milk, cheese, chopped spinach, or pasta, spinach/kale and cheese strata, enough for two days (you can use a small baking dish to make enough for a baby for two days, or make this for the whole family and serve baby leftovers).
There are also quick options you can prepare or serve daily -
Cottage cheese and blueberries,
Scrambled egg, omelette, warm, buttered, chopped hard boiled egg,
Little cubes of cheese,
Chopped up mac and cheese mixed with chopped broccoli,
Little toast fingers or squares with smooth peanut butter,
Peas,
Cooked frozen veg (diced carrots),
Toast with cream cheese,
Diced ham,
Polenta is easy to make ahead and it goes semi solid when cool - easy to cut into baby sized pieces. You can add cheese to it as it cooks.
You can make enough of the cooked foods to last for two days.
Don't put your baby in the high chair until you're ready to plonk food in front of her.