Peppermint meringue cookies are scary because the extract might melt the meringue down. Make sure you add it very slowly and keep the mixer on high while not letting it splash you. If it starts to thin, add a bit of sugar and possibly a bit more cream de tartar. This is one flavor that sometimes melts and means you need to start over which isn't fun.
Once you have all four flavors piped, place them in an oven for 6 hours at 200 degrees. Once they finish, do not remove them. Let them sit in the oven after it's been turned off over night if you can. In the morning take them out and you're done. If you don't leave them in the oven, there is a good chance they'll crack. That doesn't change them much, they're just not as pretty.
Let me know how this recipe works for you and thank you again for reading!