Combine sugars, milk, butter, and pecans in a heavy saucepan.
Bring to a boil.
Boil for 1 1/2 minutes.
Remove from heat.
Add 1 tsp. vanilla.
Beat to a cream, about 3 minutes.
Drop in spoonfulls onto greased wax paper and allow to cool.
Once the process gets going, it moves quickly, so it's important to prepare your wax (or parchment) paper before you start cooking. For a candy recipe this is pretty simple (no exact temperature requirements); however, it's important to time things exactly according to the directions. For me this means resisting the urge to start tidying up while the candy is boiling.As you beat the mixture to a cream, you'll notice - probably after about 2 minutes - that it will start to thicken up quite quickly. The exact moment at which to stop beating and begin dropping is difficult to describe, but in general it's better to guess a bit early (when it still seems runny) than late (when you could end up with one giant praline stuck to the inside of your pan). The best thing to do is to test-drop when it starts to thicken and see whether the candy runs all over the counter or whether it sets up.
The longer the mixture stays in the pan, the more rough & sugary the consistency will be. This means the final pralines you drop may not be the prettiest. I like to drop the last dregs in small, coin-size pieces in between the larger pralines. These make great "tester" pieces for the cook or other "helpers" who happen to be standing by.If you end up waiting too long to start dropping and the mixture is un-droppable, no worries. Run some water in the pan, wash it out, and start again. Chances are you have enough ingredients to make another batch, right?
However, if you do have interest in trying some variations on the classic praline flavor, there's an old Southern Living article - no longer, alas, on their website - with several different flavor possibilities using a slightly different recipe. Some helpful person has transcribed the original article at post #15 on this page.