Cream together sugar and butter, until fully mixed. Mix for about 2 minutes till light and creamy.
Mix eggs, milk and vanilla and mix in.
In a separate bowl combine the dry ingredients; flour, baking powder and salt.
Slowly pour the dry ingredients in with the wet ingredients, while stirring.
With your hands, shape the dough into a ball.
Cover the dough with plastic wrap or place it in a ziplock back and place it in the fridge for 1 hour (up to overnight).
After the dough has been chilled , separate it into 2 equal sections of dough. Keep one in the fridge while you work with the other.
Roll the dough out into a rectangle, that is about 1/4inch thick.
Spread half of the melted butter evenly over the dough, leaving about 1/2inch of space around the edges without butter.
Mix together the brown sugar and cinnamon in a small bowl.
Sprinkle half of the cinnamon sugar mixture over the butter.
Starting with the longer edge, carefully roll the dough up onto itself, rolling tightly into a log. If you get an tears, carefully try to seal them with your fingers.
Pinch the edge of the dough into the roll to seal the roll.
Wrap the dough in plastic wrap and place in the fridge to chill for another hour (up to overnight).
Repeat steps 8-14 on the second half of the dough still in the fridge.
Preheat the oven to 375 degrees.
After the dough has chilled get a really sharp knife and carefully cut each log into slices, about 1/4 inch to 1/2 inch thick.
Place the cookies on a baking sheet lined with parchment paper or a silicone liner.
Bake the cookies for 9-12 minutes until they start to lightly brown on the edges.
Remove from the oven and allow the cookies to continue cooling on the cookie sheet for another 5 minutes (if you need to reuse the cookie sheet) or until they're fully cooled.