If you just want to prepare garlic bread—assuming you're starting with already-baked bread—that shouldn't be too hard stovetop.
Heat some butter in a saucepan until water finishes evaporating (the bubbling will look different), toss in some chopped garlic, stir for 30s or so until fragrant. Remove from heat. Lightly toast the bread (in a toaster, or by holding it with metal tongs above the burner). Spread a little of the garlic butter on top of each piece. Slice a piece of fresh garlic in half, rub over bread for some extra fresh-garlic flavor.
If using garlic powder just melt butter, then add garlic powder. Then go ahead and spread on toast. Or spread plain melted butter on bread, then sprinkle with garlic powder (and, personally, although its heresy, I add a little onion powder as well).