How much do you want to have after making the food

It comes down to how much it's costing you to make the food and how much are you charging the customer. You'll have fixed costs like stove, pots and pans, utensils etc. Then you'll have recurring costs like pay roll, food ingredients, water and electricity etc. You have to make sure you are charging enough to cover all your costs and making some profit at the end of the month. It also depends on how many customers you are expecting, you have to spread the costs among all your customers. There are a lot of templates available online to help you get started on this.