Subs for milk are hard. I am only lactose intolerant.
I have not found a coffee creamer I like that does not make my coffee taste weird.
I have not found an ice cream I like that is creamy. (there are some coconut based ones that are suppose to be good but my kiddo is allergic to coconut.
In mashed potatoes, I use some of the starchy potato water with safe margarine. My kids actually do not like mashed potatoes with milk, they say they don't taste like potato.
In frosting I love to play with liqueurs and juices. I even once made blueberry frosting with blueberry syrup (for pancakes) and my kids loved it! If I don't want a flavor other than vanilla I use iced water.
Baked goods I use juices or water and I adore chocolate cake with cointreau or for really chocolate taste, a chocolate liqueur.
For Egg, I always had good luck with flax gel for things like meatloaf, meatballs, and heavier baking like pumpkin breads. For lighter baking I had some luck with applesauce. Both changed the flavor of lighter tasting pastry or cookies. For those I played....a lot......some very bad experiments. And then I discovered making cake with 7-up! Vanilla cake tasted so good again! Sometimes just adding extra baking powder to get more lift was enough. Sometimes corn starch helped hold baked goods together. There are some egg free baking cookbooks out there. I had mixed luck with them but that is where I started and then experimented from there.
As for pancakes.....I just left out the egg and upped the baking soda or powder depending on what the recipe called for. They are not as fluffy, but they are good. Heart healthy Bisquick makes up nicely without the eggs. I don't have a box right now but the website ingredient list is: Enriched Flour Bleached (wheat flour, niacin, iron, thiamin mononitrate, riboflavin, folic acid), Canola Oil, Leavening (baking soda, sodium aluminum phosphate, monocalcium phosphate), Dextrose, Sugar, Tricalcium Phosphate, Salt, DATEM, Corn Starch.
For me no two sauces are the same because I just put whatever I'm in the mood for in it. And I don't measure. There are a few things I always do. I always start by sauteing some kind of an onion (no garlic for us) and once in awhile I'll add peppers (not a favorite flavor of mine). I use shredded carrots, yep, dump the bag in or shred my own right into the pot - that's my sweetener. Salt and pepper or red pepper flakes. If I am using dry herbs I add them before a long simmer. If I am using my favorite - fresh basil, I add it for the last half hour only as the flavor seems better. I use to start from tomatoes....ummm, really did not have to start there - LOL. Now I mix some cans of crushed tomatoes, some diced tomatoes, and tomato paste (for me they have to be plain, no herbs, or spices, etc....so there is no garlic). Sometimes I add beef broth, sometimes I add red wine, those just change the flavor a bit. That's it. Mine sits on the stove for hours on low. I don't use the crock pot because it is too small for the amount I make.
Then when I want something different, from there it's my mood, mushrooms, sausage or other meat, olives, zucchini or other veggie.
One extra word of advice when making sauce in a crock pot (yes this really did happen in my single days). If you start your sauce in the morning and go to work and your friend calls with tickets to see Carlos Santana and you don't go home, by the time the concert is over and you get home.......sauce looks like baked beans! LOL! You mean my crock pot doesn't turn off by itself?