Keep in mind that not all of these work all the time!!!
SAME RATIO:
Cows milk- almond milk or flax milk
cream cheese/sour cream/heavy cream/oils- cottage cheese,Greek yogurt, ricotta cheese
oils/butter- nut butters, avocado, greek yogurt, applesauce, pumpkin puree
Flour-Pea or rice protein powder, oat flour (ground oats) garbonzo bean flour, beans
DIFFERENT RATIOS:
1 egg- 2 egg whites, 1 Tbsp egg replace+2 Tbsp water
 1 cup Flour- 1/3 cup coconut flour+1 cup water
1 cup sugar- 1/2 cup pure-via,truvia or nectresse, 2 Tbsp pure stevia or 20 stevia drops
Ask me If i Know of any other alternatives and I will tell you!