Whey isolate and water during your nutrition window. No milk, not even skim. Just whey isolate and water. If you can afford a premium protein powder. Hydrolyzed protein gives you the best / fastest absorption and the most complete amino acid profiles which will help you keep lean mass.
I eat no breakfast, just water and black coffee. Then after work I have protein/water drink before the gym then eat my rice / potato, veggies and meat bowl post workout and another shake in the last hour / 30min of my window.
Those 2 shakes add 60g of protein and only 200 calories.