Why do you want to eat 1000 calories?
What food you choose depends on goal
For example for exercise enhancement might want to eat a lot of carbohydrate
Do you want to gain muscle and not much fat?
If so it needs to be high percent carbohydrate and low percent fat and it needs to have some protein
If you do not care if you increase body fat percent then this is very easy
Most deserts have high fat calories and high carbohydrate calories and will make you gain weight fast but it will be fat weight