How to make hamburger buns as fluffy as in McDonald's?

your recipe is great.However ,here is a tip . when shaping the buns don't press on top of the bun ,just make them as balls and don't press on the top leave them for a while on the sheet without pressing the top . I hope that will work .

I have found that using russet (starchy) potatoes is always a winner. Boil a potato or two until very soft. Drain off some of the water and let it cool. Use the potato water as your yeast water. Then, completely mash/puree the potato. If this sounds odd to you, start by adding 1/4 cup of the mashed potato to your recipe and see if you like the results. Next time, increase it by 1/4 cup and see what the results are. Based on the amount of flour you are using - you shouldn't need more than 1/2 - 3/4 cup. Dried potato flakes/instant potatoes don't give you the same results. Side note/question: I don't see that you are using bread flour vs. all purpose. I prefer a certain brand's bread flour over all others.

If the buns soft but are too dense, you need a greater rise. A few suggestions:

1. Bread flour. A higher-gluten flour will generally allow more rise, by giving more support. You may need to add slightly more liquid and/or a little more fat to get the same dough moistness and softness.

2. Stretch and fold during bulk fermentation. This may not be necessary, but adding in from 1 to 3 "stretch and fold" maneuvers spread out over the bulk rise can strengthen gluten much more than extra kneading time at the beginning.

3. Tighter shaping. I don't know how you shape your buns, but if you want them to rise high in their final fermentation before baking, you may need to shape more forcefully. For the strongest rise, I'd generally be sure to stretch the "skin" of each dough lump until it is taut. For even better shaping, do a "pre-shaping" step after dividing the buns where you stretch a bit, then do a "bench rest" for 15-20 minutes (with the dough covered), then shape again (pulling tight). Roll each bun around in a circle after any previous shaping to pull the skin even more.

4. Be sure to wait for rise before baking, perhaps more than "double". I find that by pushing soft rolls/buns slightly toward what might be considered "overproofed" for other bread, I maximize rise and lightness. Obviously you can go too far and have the buns actually collapse during baking, but that generally takes a lot more extra proofing than you might think (assuming you've shaped well and are using a strong flour like bread flour).

Assuming some of these things work, you may also need to decrease the amount of dough in each bun, since they will be less dense and thus will become larger than previously.

To get a really fluffy commercial-style burger bun, you need a very soft dough, and actually I don't think you need to use a particularly high-gluten flour, but you will want to machine-knead it for a longer time and then let it slowly rise to triple instead of double after shaping, and cook it at a low temperature (~350F).

The dough might be soft enough that it may not support itself well. You can use a pan designed for making burger buns (it looks like a shallow muffin pan) or you could use a large muffin pan if that gives you large enough rolls, or you can use a sheet pan and allow the rolls to spread and flatten out, or you can use a cake pan and let them rise together and become a little bit squared off as they merge together.

The light commercial white bread structure is very different from homemade doughs. I'm learning how to achieve it, so here are some pointers:

The main objective is to make your gluten work really hard: it has to hold up twice as much air as your regular homemade bread.

Autolyse your flour first, just mix it with the water and let sit for 20 minutes.

Don't add any fats before hydrating the flour and kneading it to activate the gluten. The fats are very helpul afterward, they coat the gluten strands and keep the finished bread soft for a longer time. If you add the fat first, it keeps the gluten from activating properly.

As has been stated before, knead the dough intensely and for a long time, i.e. 20 minutes in a stand mixer. The commercial kneading process is very intense and you will see the difference in the dough's texture and ability to hold a higher water content.

Adding more wheat gluten is also a good idea.

Do tangzhong a.k.a. water roux. Take a bit of flour (recipes vary from 3 tablespoons to 1/3 of all your flour), mix it with water and heat it in a water bath pot to a temperature of 60-65 Celsius while constantly whisking to keep it from clumping. It's going to achieve a gel consistency. At this temperature, amylase enzymes activate and change some of the the starches in your flour to sugars. For best results you should hold the mixture in this range for some time, at least 10 minutes. The same process happens in your oven while heating the loaf at the start of baking. Baking at a lower temperature prolongs this stage, but once the dough reaches temperature of 68 C, amylases are deactivated for good. Some commercial bakers also just add amylase or diastatic flour for this purpose.

The commercial-type bread therefore has less starch, more sugar and more protein (gluten).

There are also other dough enhancers that make mass produced bread soft, fluffy and long lasting. Vitamin C (used in minimal amounts) makes the proofing faster and helps keep the product soft for longer. Emulsifiers like lecithin or xanthan gum can be used to hold up the gluten structure and also keep the bread fresh.