Prop a sandwich bag up inside a measuring cup or mug.
Add milk, half and half, sugar, and vanilla extract into sandwich bag and close it.
Put this sandwich bag inside the other sandwich bag and close it as well.
Put ice and salt into the gallon bag.
Place the sandwich bags inside the gallon bag and close it up.
Shake, shake, and shake some more until the ice cream mixture hardens!
Add your favourite toppings and enjoy! Some ideas are chocolate sauce, nuts, crushed up chocolate bars, and caramel.