Before anything touches the stove, I line a baking sheet with parchment paper and set it close by. I also measure every ingredient into separate bowls so nothing slows me down mid-cook. This recipe moves quickly once the sugar starts boiling, so having everything ready saves you from scrambling.
In a medium saucepan, I combine the brown sugar, granulated sugar, evaporated milk, and butter over medium heat. I stir constantly as it melts together, since sugar can catch and burn on the bottom if left alone. This base is what gives the praline its classic caramel color.
Once everything is melted, I let the mixture come to a steady boil, still stirring the whole time. I keep it boiling for about 4 to 5 minutes, or until it reaches the soft-ball stage (roughly 235-240°F on a candy thermometer). This step determines whether your pralines set creamy or crumbly.
As soon as the mixture hits that stage, I pull the pan off the heat right away. I stir in the salt, vanilla extract, and pecan halves immediately, working quickly before the candy starts to firm up in the pot. The mixture should look glossy and slightly thickened at this point.
I give the mixture a good, brisk stir for about a minute until it loses some of its shine and starts to thicken just slightly. This is the moment that tells me it's ready to scoop if I wait too long, it hardens right there in the pan.
Using a cookie scoop, I drop rounded mounds of the praline mixture onto the lined baking sheet, working fast before it firms up completely. I let them sit undisturbed at room temperature for 20 to 30 minutes until fully set and firm to the touch.