Cooking with your little ones is a brilliant way of exploring maths with them.
You could keep it simple by getting them to help make sandwiches: should you cut them into squares or triangles?; halves or quarters?; how much filling should you add?
Or maybe try a spot of baking: lots of weighing and measuring - have you got enough?; how many biscuits are you making?; do you need a big or small cutter/tin?; what temperature does the oven needs to be?; what is the cooking time?