The amount of ingredients depends on how much you are making:
Note: almost any bread will work, including bread that is slightly stale. Leftover hot dog or burger buns work, too.
Mix softened butter with garlic powder or garlic salt to taste. Spread on bread – whatever you have on hand. A loaf of French or Italian bread, cut on the diagonal will need about 3/4 stick of butter, so that will help you judge how much to make for smaller or larger amounts.
Sprinkle with cheese – here is one case where we actually like the canned cheese – it’s nutty and gets a gorgeous brown color, but if all you have is really good Parmigiano-Reggiano, that would work in a pinch:).
Place directly on top oven rack (or you could use a cookie sheet, but a rack is better; some bread on a cookie sheet will collect moisture on the bottom) and broil for several minutes. Leave the oven door open an inch or two, and watch like a hawk – it takes seconds to go from golden brown deliciousness to slightly burned.
How long it takes really varies with the type of bread you use and how far it is from the broiler. Usually three or four minutes does it.
Find it online: https://frugalhausfrau.com/2012/04/14/parmesan-toast/