I usually make "American" buttercream but sometimes get the request for frosting that isn't sweet. I go to SMBC but hate that I have to put my fondant covered cakes in the refrigerator. They always come out sticky. Also hate all of the egg yolks I waste or try to figure out a use for after SMBC. I successfully made a batch with meringue powder! Here's what I did.

Using 1:2:2 ration (because I think SMBC mainly taste like hunk o' butter)

1 cup water
2 cups sugar
1/2 cup meringue powder (NOT eggwhite powder)
2 cups unsalted butter (room temp cut into squares)
1 tablespoon vanilla extract.

Put one cup water and 2 cups sugar into mixing bowl. Place over simmering pan of water until it reaches 160 degrees (this makes sure the sugar is properly disolved) Remove from water bath and cool to warm. (Warm is when I could comfortably put my hands on the side of the bowl but not so cool as room temp.) Slowly add the meringue powder until disolved into sugar mixture. Using whip attachment, beat on high until peaks form. (mine weren't super stiff peaks) Switch to paddle on low spead and begin adding butter pieces. (I just sort of threw butter hunks in one at a time without waiting inbetween). Turn on medium speed and walk away from the mixer. Do other things until you hear a slapping sound. Add the vanilla and viola! SMBC that requires no refrigeration!

Make changes, give feedback Thanks!!

i will try it and see! i normally buy the egg whites in a carton though. but sometimes i don't have time to run to the store to buy more if i'm out, i always have meringue powder on hand for royal icing. i tried to make it before by dissolving the meringue powder with the sugar in the water, but it became grainy and never dissolved, i suspect that it may have cooked the powder before the sugar was able to dissolve?