Start by heating your milk to 110 - use a pan and a thermometer - if you don't have a thermometer heat over low heat for about 3-4 minutes until the milk is warm to the touch but not hot
Add the milk, 1/4 tsp of sugar, and yeast to a bowl and let it sit for 10 minutes until the yeast has frothed and bubbled
Add the egg yolk, butter, and sugar to the milk, yeast mixture and lightly whisk
Add the flour and salt and use a wooden spoon to mix all ingredients together until a thick clumpy mixture forms.
Using your hands, knead the dough until a smooth ball forms (about 30 seconds)
Grease your bowl and return the dough ball to the bowl
Cover with a warm damp cloth and set somewhere warm to rise for about 60-90 minutes or until the dough is about 1.5x bigger (See Note 2)
Meanwhile, combine 2 tbsp of softened butter, 1/3 cup of dark brown sugar, and 1 tsp of cinnamon with a spatula until a paste forms
Once the dough has risen turn it on to a floured surface and gently work the dough into a rectangle with your hands
Using a rolling pin, roll out the dough into a long rectangular sheet
Spread the butter, brown sugar mixture along the entire sheet until the whole thing is covered evenly
Roll the dough up and use twine, string, or a sharp knife to cut four even cinnamon rolls
Place the rolls in a small baking pan (see Note 3) and cover with a damp towel and set aside for another 60-90 minutes for the second rise
Preheat your oven to 350 degrees while the rolls do their second rise (See Note 4)
When Cinnamon Rolls have increased in size by about 1.5x they are ready to bake. Cook for about 25-30 minutes until the tops are a deep golden brown and the sugar has caramelized - watch carefully as cook time will vary slightly
Let cool for about 20 minutes before frosting