How to simulate an oven when what you actually have is a gas stove?

Dutch oven

(a proper cast iron one, mind you)

• Put your dutch oven on the stove top with the lid on, and turn on the heat until it gets hot
• Place the thing(s) to be baked inside (but not directly touching the sides or bottom; a little rack or other standoff will be helpful)
• Put the lid back on and turn the heat way down
• Wait. And this is a bit of a problem because it is hard to know the exact temperature, so baking is tricky.

This is also how one bakes over a campfire, though there you use coals and can get a reasonably repeatable temperature. Works better with cobbler than cake (I have seen cakes done this way, but more often I've seen them messed up), but it should do garlic bread just fine.

The pure mass of the iron serves to smooth out the uneven heating from the stove. This is also the reason a proper dutch oven has a lip on the lid: so you can put some coals on there to insure the lid stays properly hot too.

Here is a link to a Coleman Camp Oven available on Amazon which is designed to sit a top a two burner gas stove. While it's principal purpose is to allow one to bake in the great outdoors this may be an easy and inexpensive option that will work for you. (I assume either Amazon will ship to you, or something competitive can be found in India)

A second option would be a counter top oven, like this one from Hamilton Beach. There are similar products from Oster and Rival as well.

Either of these options should serve to get you an oven you can work with for more than just garlic bread, but a full range of baking and roasting activities.

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).

I make garlic bread, Naan style on the stove top. You can use a basic bread dough like Hugh Fernley Whittingstalls basic bread dough (google it). Just prepare the dough, shape it into flat breads and cook on a skillet or frying pan. I mix garlic and herbs into the dough mix and put garlic butter ontop. Took a few tries to get it right but worth some experiments!

If you have a large pot or wok made of heavy material (cast iron or cast aluminum) with a lid (or two woks of similar size, use one as a lid) and a metal trivet or short tin can, you can improvise a stove-top oven. And a baking pan that will fit inside.

Put the pot/wok on the stove, with the trivet/can inside. Cover and heat. Once it has heated up, put the baking pan with whatever you want to bake on top of the trivet/can and cover.

Bake time is a guessing game; let your nose and experience be the guide. I have successfully used this method for muffins, banana cake, PB cookies.