Preheat your oven to 375 degrees. Grease a donut pan and set aside.
In a large microwaveable bowl, melt the butter. Then, mix in the sugar and lemon zest and put it aside to cool slightly.
In a separate bowl, whisk together the milk, lemonade, egg and food coloring until everything is well combined. I know this mixture might look a little odd and the lemonade will cause the milk to curdle slightly but I promise it’s totally ok!
Into the butter mixture, add the baking powder and baking soda. Stir to combine.
Lastly, gently but swiftly, fold in the flour and the liquid ingredients, continuing to fold just until combined. There may be a few spots that don’t get any food coloring, which is completely fine as you definitely don’t want to over mix the batter.
Scoop about 3 heaping tablespoons into each well-greased donut cavity, using a spoon to evenly spread the batter around (you can also gently tap the entire pan on a counter top a few times once you’ve filled all the donut cavities up).
Bake for 8-9 minutes, or until the donuts are springy to the touch. Allow them to cool in the pan for 5 minutes before removing them to a baking rack to cool completely.