In a bowl, place all the ingredients except the butter. You can use a stand mixer using the hook attachment on medium speed to mix everything together. If you don't have one, first use a spatula to mix and when it doesn't help anymore, continue with your hands.
Knead for 5 minutes in a stand mixer or by hand for 10 minutes. The dough should look homogeneous and more elastic than when you started.
Add half the butter and knead with a mixer or by hand. At first, you will feel like it's not coming together and something went wrong. Be a little patient and it will come together and it will look very good.
Add the other half of butter and knead more. The second inclusion of butter will be easier than the first ;).
Knead until the dough feels very smooth and elastic, about 5 minutes since the butter is completely incorporated.
Place the dough in a bowl, cover it and let it proof in a warm spot for 1 hour.
Weigh the dough and divide it into 12 equal portions.
Form buns by flattening the portions, and folding the edges onto the centre. Turn it around and turn them against the table to close the joining. Avoid using a dusted flour surface at this point.
Cover them and let them rest for 15 minutes.
One by one, turn them over, flatten them with the palm of your hand and roll them into a long bun. Turn them around and push on their side using your fingers so that the friction closes the place the dough joins. You can see how it's done on the video lines above.
Place them on a baking tray lined with baking paper or a silicone mat. Leave a good space between them because they grow a lot in the oven.
Cover them and let them proof for an extra 20min.