Line a baking sheet or flat surface with parchment paper.
Lay the pecans on a rimmed baking sheet and bake at 375 for 7 minutes or until they start to release their oils. Pull from oven and toss with about a little butter and a sprinkling of salt. Set aside to cool completely.
In a 3 quart saucepan, heat the 4 tablespoons of butter until it is partially melted, then add the ½ cup cream and heat butter and cream together just long enough to melt the butter. Remove from heat and (off heat) add both sugars and water stirring until mixture is uniformly blended. If sugar mixture has splashed up onto inside walls of pan, wipe it clean. Also, clean the spoon .
Set the pan back on the stove and insert a deep fry candy thermometer in center. Heat over medium, stirring only occasionally, until candy reaches 235 to 236 (soft ball stage). You don’t have to stir constantly at first. Let it heat up until it gently starts simmering, then allow it to simmer/low boil with the temperature rising slowly and steadily. This should take 10 to 12 minutes.
Remove from heat and add salt, vanilla and toasted pecans, then stir with a wooden spoon for several minutes until mixture is thick enough not to flow everywhere when dropped from a spoon. Note that it may seem hopelessly loose at first, but if you heated it to soft ball stage it will start to thicken. When it does, quickly drop by large spoonfuls onto the parchment paper.
Let the pralines set, then peel off the parchment.