Prep Your Station. Before starting, you want to have everything prepared, measured, and close by so you can work quickly. Every second counts when you're making candy, so you don't want to waste any time or risk burning your candy! Line 2 sheet pans with parchment paper and have a small cookie scoop or two spoons close by for measuring the pralines out at the end.
Toast & Chop Pecans. To start, toast spread the pecans out onto a baking sheet and toast 8-10 minutes at 350 degrees F until fragrant and toasted. Let them cool on the baking sheet, then roughly chop pecans and set aside. (This can be done a few days in advance, if desired!)
Combine. In a heavy bottomed 3-quart saucepan, combine brown sugar, heavy cream, corn syrup, and salt. Stir until well blended. Attach a candy thermometer to the side of your saucepan.
Boil to 235 Degrees F. Bring the mixture to a boil over medium heat (this can take 12-15 minutes!), then boil 5-7 minutes, until the sugar mixture reaches 235-240 degrees F. on the candy thermometer. This is known as the "soft ball" candy stage--if you drizzle a drop into a glass of ice water, it should form a soft ball, rather than a stringy mess or a hard ball. Keep in mind that if you do not reach 235 degrees, your candy will not set up properly. This is the key step!
Stir in Butter. When the sugar mixture reaches 235 degrees F, stir in the butter and stir until melted.
Stir in Pecans & Vanilla. Remove the pan from the heat and stir in the pecans and the vanilla. Stir until well blended (and to help the candy mixture cool down a bit!) about 4-5 minutes.
Scoop. Use a small cookie scoop or two spoons to scoop heaping tablespoon-size dollops of pralines out onto your parchment-lined baking sheets. The mixture will begin to set up and turn more opaque.
Cool to Set. Allow the pralines to cool and set completely. This can take an hour or more, depending on your temperature & humidity. When freshly scooped, the pralines may be more glossy & translucent, but they will start to turn more opaque and fudgy with time.
Serve & Store. Enjoy right away or store in an airtight container at room temperature up to 1 week.