Preheat oven to 350°
Start by making the dough, add all dry ingredients into a bowl and whisk together.
Add butter with your hands, don't overwork it, but incorporate it all the way through.
Add the milk, again don't overwork it, but fold it in.
When all ingredients have come together, let it rest a little to rise.
Once the dough has risen, place on a board to roll out. Spread flour under, around and over the dough to help with the rolling process.
Use a rolling pin to stretch the dough into a rectangular shape about 12"x15".
Take room temperature butter and smear it all over the top side of your dough spreading it to the edges.
Combine the sugar mix ingredients in a small bowl and then sprinkle on top of the buttered dough.
Roll, tuck first on one side to start the roll. This doesn't need to be tight. Don't press, just let it do its thing.
Close the edges of your roll off by curling your hands around them and pressing. This will look like a log.
Mix your custard together in a small pot. While occasionally stirring, bring the custard mixture to a boil, then immediately take it off the stove.
Cut your butter roll log into 2" sections. You should be able to get 8-10 cuts.
Spray your pan or lather it up with butter. Make sure to get the sides.
Place the rolls into the pan, they shouldn't touch but it's ok if they do.
Take the custard (it should still be warm) and drown the rolls with it. It should cover more than half of their height.
Place in the oven at 350° for 45 minutes.