I've done a lot of experimenting with royal icing. I've tried cooked egg whites, corn syrup, the meringue powder recipe from Wilton, from Sugarbelle, from Bake at 350. And honestly, I hated them all. They hurt your teeth, they were lemony and sour, they had a weird flavor, and they weren't sweet enough. Finally, after lots of trial and error, I have created a recipe that works for me. It's sweet, it doesn't hurt your teeth, and it doesn't have that weird meringue powder lemon taste. Do whatever works for you, but here's the recipe that works for me.
1 T. meringue powder (I used Wilton's)
3 T. water
2 c. powdered sugar
Mix and enjoy.
I didn't even use a mixer, I simply stirred the mixture by hand and it was perfect. This recipe was for a thick royal icing used for piping.
I put it in a plastic bag with a piping tip and used it to outline and decorate cookies.
To create a flood consistency, simply add a bit more water. Here I added about 2 T. of water for a perfect glaze consistency. If you cut through the bowl of icing with the spoon, it should take about 2-3 seconds for the frosting to settle.
You don't need a tip for the glaze, just scoop into a bag and snip off the tip. Add more powdered sugar/water to adjust your consistency. This recipe is so easy and has just enough powdered sugar to taste really good without being extremely thick. From now on, this is all that I'll use for my cookies. I highly recommend it!