Mix all the dry ingredients (minus cardamom) in a bowl.  Put the yeast and salt on separate sides of the bowl, because the salt can mess with the yeast's ability to activate.

In a small saucepan stir together the butter and milk until the butter melts, and add the cardamom as well.  Heat it up to around 98.6 degrees---keep a close eye, because you don't want it to boil!

Once the milk and butter mixture has cooled a bit (it needs to be at least below the 98.6 F temp), add it to the dry ingredients and mix it all together.  I prefer to do this in my stand mixer and add the liquid slowly while the mixer is on low.  Put cling wrap over the bowl and let it rise at least 30 minutes in a lukewarm place (the dough should double; for me this is more like an hour).

Once the dough has doubled in size, sprinkle some flour on your counter and roll out the dough.  It helps to make the dough into a rectangle shape to begin with, then use the rolling pin to keep it that way as you roll it out decently thin.  You can see in my pictures the thickness I used---there's no rule for what it should be, I just like a lot of filling so wanted thinner dough.

Soften some butter until it's spreadable and spread onto your rolled-out dough.  Sprinkle on the cinnamon and sugar to your own taste (I like mind to be super gooey), then roll it up.  On one of the long sides, tack the dough to the counter with your fingers, then start rolling from the other side (keeping it long).  Try to get a nice, tight roll with no gaps.  Once it's rolled up, make sure the dough sticks to seal the roll, then use a sharp serrated knife or a scraper to cut pieces about 1 inch apart.

Line a baking sheet with parchment paper and place the dough pieces, leaving plenty of spaces between them.  Cover with a large plastic bag (or kitchen towel) and let them sit in a lukewarm place for about 30-45 minutes for additional rise.  Preheat your oven to 435 F (or 225 C).  Right before popping them in the oven, mix up a quick egg wash and use a pastry brush to add a layer to the top of the buns.

Bake for 13-15 minutes, until they are golden on top. Let them rest for 10-15 minutes after you take them out of the oven before eating.